Method for training woman's pelvic floor muscles

Abstract

FIELD: physiotherapy.SUBSTANCE: invention relates to training the pelvic floor muscles of women, in particular to training methods using biofeedback (BFB) techniques. A primary and final examination is carried out to assess muscle condition, as well as an individual selection of a training course containing active and passive components. The active part of the course is carried out using hardware and software with biofeedback (BFB). Three stages of exercises are performed in a strict sequence: cyclic toning tension and relaxation of the entire muscle group. Then separate forceful tension and relaxation are carried out alternately in the front and back muscle groups. Next, separate controlled tension maintenance and relaxation of the anterior and posterior groups of pelvic floor muscles are performed alternately. After that, the passive part of the course is carried out by inserting into the vagina and wearing it daily a selected egg-shaped vaginal microtrainer. In this case, the active and passive parts are alternated, and the parameters of the course, including the size of the microtrainer, are adjusted based on the data obtained using biofeedback at the stage of force tension and the stage of separate controlled maintenance of tension and relaxation of the pelvic floor muscles of the active part.EFFECT: method ensures an increase in the effectiveness of pelvic floor training in women, objectively expressed in a reduction in the time required to achieve training results.5 cl, 2 tbl, 5 ex

Description

[0001] The invention relates to the field of training the pelvic floor muscles of women, in particular to training methods using the biofeedback (BFB) technique [A63B23 / 00, A61H19 / 00].

[0002] A METHOD FOR TRAINING THE PELVIC FLOOR MUSCLES OF A WOMAN is known from the prior art [Basic Obstetrics and Gynecology Clinic. Current Issues in Urogynecology. Pelvic Floor Muscle Rehabilitation System. Educational and Methodological Manual for Residents and Practicing Physicians. Krasnodar. 2017, 27 p.] including an initial and final examination of the vagina, a training course lasting 15-20 sessions, consisting of periodic tension and relaxation of the pelvic floor muscles, while the training is carried out using software and hardware operating on biofeedback (BFB) technology.

[0003] A disadvantage of this analogue is the lack of effectiveness of the training process, resulting in an increased time required to achieve sustainable functional results. Furthermore, the known method does not include a passive training component, implemented through daily wearing of an individually selected vaginal microtrainer. As a result, the impact on the pelvic floor muscles is limited to periods of active training, which reduces the overall training load and delays the achievement of results. Another disadvantage of the known method is the lack of interim assessments and dynamic adjustment of course parameters based on objective data obtained during training.

[0004] The closest in technical essence is the DEVICE FOR TRAINING THE PELVIC FLOOR MUSCLES "PELVIC-FIT" AND THE CORRESPONDING METHOD [pelvic-soft.site123.me / Каталог / ПРИПОР-ФИЗИОТЕРАПЕВТИКСКИЙ-АМБЛИОТРОН-вид-исполни-pelvic-fit], including a training course lasting 15-20 sessions, consisting of periodic tension and relaxation of the anterior and posterior muscles of the pelvic floor, while the training is carried out using software and hardware that operates on biofeedback technology (BFB), the minimum number of training is 3 times a week, the duration of tension of muscle groups is 30-60 seconds, the relaxation period is 15-45 seconds, and training is also possible through muscle tension without a time limit, as long as the state of the body allows.

[0005] The main technical problem with the prototype is the insufficient effectiveness of the training process, manifested in the increased time required to achieve a stable functional result. This is because the existing method consists of periodic tension and relaxation of the anterior and posterior pelvic floor muscles without a strictly defined sequence of functionally distinct exercise stages. Specifically, it fails to ensure the gradual development of muscle tone, strength, and the skill of sustained, controlled tension, which reduces the focus and effectiveness of the training.Another drawback of the known solution is the lack of a passive training component, implemented through daily wearing of an individually selected vaginal microtrainer. This means that training is carried out exclusively within the framework of active sessions, conducted a limited number of times per week. This reduces the overall load on the pelvic floor muscles and delays the achievement of the desired functional effect.

[0006] The objective of the invention is to eliminate the shortcomings of the prototype.

[0007] The technical result of the invention consists in increasing the effectiveness of pelvic floor training in women, objectively expressed in a reduction in the time required to achieve the training result.

[0008] The said technical result of the invention is achieved due to the fact that the method for training the muscles of the pelvic floor of a woman includes a primary and final examination to assess the condition of the muscles, as well as an individual selection of a training course containing an active and passive part, based on the examination data, during which the active part of the course is carried out using a software and hardware device with biological feedback (BFB), three stages of exercises are performed in strict sequence:

[0009] - carry out cyclic toning tension and relaxation of the entire muscle group;

[0010] - then carry out separate forceful tension and relaxation alternately of the front and back muscle groups;

[0011] - and then carry out separate, controlled maintenance of tension and relaxation alternately of the anterior and posterior groups of pelvic floor muscles;

[0012] then the passive part of the course is carried out by inserting into the vagina and wearing it daily a selected egg-shaped vaginal microtrainer, while the active and passive parts are alternated, and the parameters of the course, including the size of the microtrainer, are adjusted based on the data obtained using biofeedback at the stage of force tension and the stage of separate controlled maintenance of tension and relaxation of the pelvic floor muscles of the active part.

[0013] In particular, examinations are carried out both intravaginally, that is, with the installation of sensors or devices in the vagina, and non-intravaginally, that is, without the installation of sensors or devices in the vagina.

[0014] In particular, the selection of training is carried out both by a specialist and using the Pelvic-Fit device.

[0015] In particular, the selection of micro-trainer is carried out by a specialist.

[0016] In particular, the passive part of the course is carried out by inserting into the vagina and daily wearing a selected vaginal microtrainer of an egg-shaped form in one of three sizes - small 1x1.5 cm, medium 1.3x2 cm or large 1.5x2.5 cm.

[0017] Implementation of the invention.

[0018] The pelvic floor muscle training method for women is a comprehensive program based on objective diagnostic data, individualized parameter selection, and the sequential implementation of clearly structured steps. The program begins with an initial examination to assess the initial condition of the pelvic floor muscles and mucous membranes. The results of this examination form the basis for developing a personalized training program.

[0019] The initial examination is designed to determine the functional state of the pelvic floor muscles, including their tone, contractile strength, relaxation ability, and tension retention, as well as the coordination of the anterior and posterior muscle groups. The examination can be performed intravaginally, with the insertion of sensors or devices directly into the vagina to obtain objective and accurate data, or non-intravaginally, without the internal insertion of devices, which increases comfort and accessibility.

[0020] The results of the initial examination are processed using software and hardware, with the measured signals digitally processed, filtered, and analyzed. Based on the data obtained, the specialist creates a customized training program, determining the parameters of the active and passive parts, their duration, sequence, and intensity.

[0021] Throughout the course, two video assessments are conducted (before and after) to monitor the progress of the pelvic floor muscles and assess the effectiveness of the training. At the end of the course, a final assessment is performed to objectively evaluate the results achieved and compare them with baseline values.

[0022] This individually tailored course consists of two complementary and methodically alternating parts: active and passive. The active part of the course is carried out using specialized hardware and software systems that operate on the principle of biofeedback (BFB), such as the Pelvic-Fit devices.

[0023] The hardware and software system includes measuring sensors, a signal processing unit, and software. The software receives signals characterizing pelvic floor muscle activity, converts them into digital form, filters out interference, analyzes, and displays muscle activity parameters in real time as graphical, numerical, and / or visual animation indicators. Furthermore, the software generates training scenarios, monitors exercise performance, records the results of each workout, and stores the data for subsequent analysis by a specialist.

[0024] A critical element of the method is the strictly sequential execution of three stages of exercises within each active workout, with the software setting the specified sequence and eliminating the possibility of its arbitrary change.

[0025] The first stage involves cyclical toning tension and relaxation of the entire pelvic floor muscle group. At this stage, the software sets parameters for the duration of tension and relaxation, the number of repetitions, and the total time of the stage. This stage is aimed at increasing overall muscle tone, improving circulation, and restoring neuromuscular connections, while biofeedback allows the patient to adjust the movements in real time.

[0026] The second stage involves alternately contracting and relaxing the anterior and posterior pelvic floor muscle groups. The software generates separate tasks for each muscle group, ensuring their isolated activation. During this stage, contraction force, signal amplitude, and force increase dynamics are recorded, which are used to objectively assess the current muscle fitness level.

[0027] The third stage is dedicated to separate, controlled tension holding and subsequent relaxation of the alternating anterior and posterior pelvic floor muscle groups. At this stage, the software sets the parameters for tension holding time and acceptable deviations in muscle activity, while monitoring signal stability, which helps develop the skill of prolonged and isolated muscle control necessary for maintaining physiological functions.

[0028] The data obtained during the second stage (strength tension) and the third stage (controlled tension maintenance) are diagnostically significant and are used to analyze the dynamics of the training process. This data is saved and analyzed by a specialist for subsequent adjustment of the course parameters.

[0029] The passive part of the course involves inserting a custom-fitted, egg-shaped vaginal microtrainer into the vagina and wearing it daily. Wearing the microtrainer provides a constant, yet gentle, physiological load on the pelvic floor muscles, promoting their toning and strengthening the skill of maintaining tension in conditions similar to natural, everyday activity.

[0030] The vaginal microtrainer is individually selected by a specialist and comes in one of three standard sizes: small - 1 x 1.5 cm, medium - 1.3 x 2 cm, or large - 1.5 x 2.5 cm. The size is selected based on the woman's anatomical features, the initial data, and the information obtained through biofeedback in the second and third stages of the active part of the course. During the course, the microtrainer size can be adjusted as the pelvic floor muscle functionality improves.

[0031] The active and passive parts of the course are methodically alternated throughout the training process. Course parameters, including the intensity of active training, the duration of stages, and the size of the vaginal microtrainer, are adjusted by a specialist based on objective data obtained in real time using biofeedback software and hardware.

[0032] Examples of use of the claimed invention.

[0033] Example 1.

[0034] A 32-year-old woman presented with complaints of decreased pelvic floor muscle tone after childbirth. Her medical history included one uncomplicated vaginal birth, with no significant underlying medical conditions. An initial intravaginal examination of the pelvic floor muscles using biofeedback software and hardware revealed a decrease in signal amplitude during voluntary and forced muscle contraction, as well as an inability to sustain tension for more than a few seconds, indicating decreased strength and endurance of the pelvic floor muscles.

[0035] Based on the diagnostic data, a customized training course was developed (10 sessions lasting from 20 to 40 minutes). It included an active portion with three exercise phases and a passive portion using a small, egg-shaped vaginal microtrainer measuring 1 x 1.5 cm. Active training was conducted using biofeedback twice a week. After just six sessions, the biofeedback software recorded an increase in signal amplitude during the separate force tension phase and improved signal stability during the controlled tension maintenance phase. Based on the examination results, a transition to a medium-sized microtrainer measuring 1.3 x 2 cm was made. Improvement in pelvic floor muscle function was objectively documented after completing the full course, reflected in increased contraction strength and the ability to maintain tension.

[0036] Example 2.

[0037] A 45-year-old woman with a history of two births and age-related changes associated with a feeling of decreased pelvic floor muscle control. The initial examination was conducted using biofeedback, in which the patient performed exercises that separately contracted the anterior and posterior muscle groups. Signal analysis revealed a marked asymmetry in muscle function, with the posterior group characterized by a smaller amplitude of forceful contraction and a rapid decline in signal strength when maintaining contraction.

[0038] A customized training program was developed based on the identified asymmetry and included an active component with an emphasis on the second and third stages of the exercises and a passive component using a medium-sized 1.3 x 2 cm vaginal microtrainer. Active training was performed three times a week. After five sessions, the biofeedback software recorded an equalization of the contraction force of the anterior and posterior muscle groups and an increase in the time it took to hold tension. Based on objective data, a specialist selected a larger 1.5 x 2.5 cm microtrainer. Improvement in the functional state of the pelvic floor muscles was achieved after 10 sessions of the program, as confirmed by the results of the final examination.

[0039] Example 3.

[0040] A 28-year-old woman with no history of childbirth presented with complaints of difficulty in voluntary control of her pelvic floor muscles. The initial examination was performed non-intravaginally using a biofeedback system. The diagnostics revealed poor reproducibility of muscle contractions and signal instability during the tension maintenance phase, indicating an insufficiently developed neuromuscular connection.

[0041] The individual training course included an active component with step-by-step exercise performance and a passive component using a small 1x1.5 cm vaginal microtrainer. Active training was conducted twice a week. After just six 30-minute sessions, the biofeedback software recorded signal stabilization and improved exercise accuracy. After 10 sessions, sustained improvements in pelvic floor muscle control were achieved, as confirmed by the final assessment.

[0042] Example 4.

[0043] A 52-year-old postmenopausal woman presented with complaints of decreased pelvic floor muscle tone. An initial examination was performed intravaginally using biofeedback. The diagnosis revealed decreased contractile strength and an inability to maintain tension for a long time, especially with separate muscle activation.

[0044] The training course was designed with a reduced initial load and included an active part using biofeedback and a passive part using a small 1 x 1.5 cm vaginal microtrainer. The training sessions consisted of 10 sessions of 20-40 minutes each. As the course progressed, and based on biofeedback data obtained during the strength training and controlled tension maintenance phase, the microtrainer size was successively increased from small to medium and then to large. Improvement in pelvic floor muscle function was objectively recorded after 7 sessions, reflected in increased contraction strength and more stable tension maintenance.

[0045] The technical result of the invention consists in increasing the effectiveness of pelvic floor training in women, objectively expressed in a reduction in the time required to achieve the training result.

[0046] The said technical result of the invention is achieved due to the fact that the method for training the muscles of the pelvic floor of a woman includes a primary and final examination to assess the condition of the muscles, as well as an individual selection of a course of training, containing an active and passive part, based on the examination data, during which the active part of the course is carried out using a software and hardware device with biological feedback (BFB), three stages of exercises are performed in strict sequence:

[0047] - carry out cyclic toning tension and relaxation of the entire muscle group;

[0048] - then carry out separate forceful tension and relaxation alternately of the front and back muscle groups;

[0049] - and then carry out separate, controlled maintenance of tension and relaxation alternately of the anterior and posterior groups of pelvic floor muscles;

[0050] then the passive part of the course is carried out by inserting into the vagina and wearing daily the selected egg-shaped vaginal microtrainer, while the active and passive parts are alternated, and the parameters of the course, including the size of the microtrainer, are adjusted based on the data obtained using biofeedback at the stage of force tension and the stage of separate controlled maintenance of tension and relaxation of the pelvic floor muscles of the active part.

[0051] To confirm the stated technical result—increasing the effectiveness of pelvic floor muscle training in women, objectively expressed in a reduction in the time required to achieve target indicators—a specialized analysis was conducted and long-term empirical data was reviewed.

[0052] The analysis was conducted to comparatively evaluate the effectiveness of the proposed comprehensive method. Five women aged 28 to 42 years with varying baseline pelvic floor muscle function participated in the study. The method included the following sequential stages:

[0053] A) Initial diagnosis: A gynecological examination was performed to assess the initial tone, strength, and ability to voluntarily contract the pelvic floor muscles. Based on the diagnosis, a personalized program was developed for each participant. The load parameters for active training on the biofeedback device (BFB) were individually selected, along with the size of the egg-shaped microtrainer for the passive part, corresponding to the anatomical features.

[0054] B) Active part: was carried out according to a three-stage formula on a device with biofeedback, which allowed the participant to visualize muscle activity and adjust the effort in real time.

[0055] B) Passive part: in the intervals between active training sessions, the selected microtrainer was worn to maintain muscle memory and stimulate the formation of a conditioned reflex.

[0056] Upon completion of the course, all participants demonstrated positive results (see Table 1): a balance of consciously controlled tone and consciously controlled relaxation was achieved, muscle strength was significantly increased, and isolated control of the anterior and posterior pelvic floor muscle groups was improved. The key quantitative result was a reduction in course duration. Each participant achieved the target level of muscle strengthening 20–30% faster than expected using only established active training methods (without the passive component or biofeedback). The experiment clearly demonstrated the synergistic effect of combining four key elements of the proposed method: 1) a structured active phase, 2) passive stimulation with a microtrainer, 3) the biofeedback principle, and 4) complete individualization of the course.

[0057] Table 1

[0058] Experimental confirmation of the effectiveness of the claimed method

[0059] Age Active training Passive wearing Initial tone / strength Result after 6 weeks Reducing the time to achieve the goal 28 3 times / week 1–2 hours / day average high tone, increased muscle strength by 35% ~25% faster than standard methods 34 4 times / week 2–3 hours / day short medium tone, improved muscle control ~30% acceleration compared to well-known courses 31 3 times / week 1 hour / day average high tone, decreased vaginal volume ~28% reduction in time to reach goal 42 2 times / week 2–3 hours / day short medium tone, improved conscious control ~20% speedup compared to standard training 37 4 times / week 1–2 hours / day average high tone, 40% increase in muscle strength ~27% reduction in time to achieve results

[0060] Analysis of long-term empirical data.

[0061] Many years of practical application of the proposed method allowed us to collect and systematize statistical data objectively comparing its effectiveness with that of the prototype method. To ensure a fair comparison, pairs of patients were formed with as similar baseline parameters as possible: age, obstetric history (number of births), and primary diagnosis. The effectiveness criterion was the objectively measurable number of training sessions required to achieve a stable target result (symptom relief, increase in muscle strength to normal values).

[0062] The data presented in Table 2 clearly demonstrate the sustainable advantage of the claimed method.

[0063] Table 2

[0064] Comparison of the effectiveness of training using the stated method and the prototype method

[0065] Description of a woman exercising Number of sessions to achieve training results The stated method Prototype 1. 54 years old, 2 children, teacher 2. 53 years old, 2 children, cashier 10 sessions 14 sessions 1. 44 years old, 1 child, accountant 2. 45 years old, 1 child, municipal employee 9 sessions 13 sessions 1. 27 years old, 1 child, postpartum urinary incontinence 2. 25 years old, 1 child, postpartum urinary incontinence 11 sessions Session 15 1. 38 years old, 2 children, pelvic pain 2. 38 years old, 2 children, pelvic pain 10 sessions 12 sessions 1. 21-year-old female student with stress urinary incontinence 2. 20-year-old female student with stress urinary incontinence 10 sessions 13 sessions 1. 25 years old, 1 child, episiotomy 2. 25 years old, 1 child, episiotomy 12 sessions 18th session 1. 25 years old, no children, painful menstruation 2. 24 years old, no children, painful menstruation 11 sessions 14 sessions 1. 50 years old, 2 children, urinary incontinence during coughing 2. 51 years old, 2 children, urinary incontinence during coughing 13 sessions 19th session 1. 30 years old, 1 child, anorgasmia 2. 31 years old, 1 child, anorgasmia 10 sessions 15 sessions 1. 35 years old, 1 child, painful menstruation 2. 35 years old, 1 child, painful menstruation 10 sessions 14 sessions 1. 31 years old, no children, hysterectomy 2. 32 years old, no children, hysterectomy 12 sessions 20 sessions 1. 36 years old, 3 children, postpartum urinary incontinence 2. 37 years old, 3 children, postpartum urinary incontinence 11 sessions 16th session

[0066] Analysis of the data in Table 2 shows that the proposed method achieves results on average 4-6 sessions (or 20-30%) faster than the prototype method, regardless of the patient's age, medical history, and initial condition. This reduction is statistically significant and clinically important, as it reduces the overall time and resource burden on the patient.

[0067] Conducting initial and final pelvic floor muscle assessments provides objective data on the functional state of the muscles at various stages of training. This allows for the assessment of the dynamics of changes and the timely detection of intermediate results, which prevents excessive training and thereby reduces the time required to achieve the desired functional effect.

[0068] Individualized training program selection based on assessment data ensures that the load matches the individual woman's baseline functional capabilities. By eliminating universal, generic training regimens, the training impact is more targeted, allowing for faster improvements in muscle function and, consequently, increasing the effectiveness of the training process.

[0069] The active part of the course, implemented using hardware and software based on biofeedback technology, provides objective exercise monitoring and allows the patient to adjust muscle activity in real time. This accelerates the development of correct motor skills and reduces the time required to achieve sustainable training results.

[0070] Performing the active exercises in a strict three-stage sequence ensures gradual development of the functional characteristics of the pelvic floor muscles. Cyclical toning tension and relaxation of the entire muscle group in the first stage prepares the muscles for the load and improves neuromuscular communication, which increases the effectiveness of subsequent stages and reduces the overall training time.

[0071] The implementation of separate strength tension and relaxation of the anterior and posterior muscle groups in the second stage ensures a targeted increase in strength and the elimination of functional asymmetries in the pelvic floor muscles. This allows for faster achievement of the desired strength level compared to training without separate muscle groups.

[0072] Performing separate, controlled tension and relaxation exercises, alternating between the anterior and posterior muscle groups, in the third stage develops the skill of long-term voluntary control of the pelvic floor muscles. Developing this skill is the final stage of functional recovery and allows for a reduction in the total number of training sessions required to achieve results.

[0073] The passive part of the course, implemented by inserting and wearing a custom-fitted, egg-shaped vaginal microtrainer into the vagina daily, provides additional physiological stimulation to the pelvic floor muscles outside of active training. The continuous stimulation increases the overall training load, which facilitates faster achievement of functional results.

[0074] Alternating active and passive parts of the course provides an optimal combination of targeted active exercise and supportive passive stimulation of the pelvic floor muscles. This combination increases the effectiveness of the training process and reduces the time required to achieve lasting results.

[0075] Adjusting the course parameters, including the size of the vaginal microtrainer, based on biofeedback data obtained during the strength tension phase and the separate controlled tension maintenance phase, ensures that the training load is adapted to the current functional state of the muscles. This eliminates both insufficient and excessive loads, directly contributing to accelerated training results.

[0076] Conducting intravaginal examinations, with the insertion of sensors or devices into the vagina, allows for more accurate and objective data on the condition of the pelvic floor muscles, which increases the reliability of dynamic assessments and the accuracy of course parameter adjustments, thereby reducing the time to achieve results.

[0077] Conducting examinations non-intravaginally, without inserting sensors or devices into the vagina, increases the comfort of the procedures and makes training accessible to a wider range of women. This allows for regular examinations and timely course corrections, positively influencing the effectiveness of training.

[0078] Specialist training selection ensures professional interpretation of examination and biofeedback data, as well as the correct development of the training process. This reduces the risk of errors in the selection of exercise parameters and facilitates faster achievement of the desired functional result.

[0079] Training with the Pelvic-Fit device ensures stable and reproducible implementation of biofeedback technology, which increases the reliability of control over the training process and helps reduce the time to achieve results.

[0080] A specialist selects a vaginal microtrainer to ensure its size and weight are appropriate for the functional capabilities of the pelvic floor muscles at a specific stage of the course. This increases the effectiveness of the passive portion of the training and accelerates results.

[0081] Using an egg-shaped vaginal microtrainer in one of three standard sizes—small, medium, or large—allows a gradual increase in passive load depending on the dynamics of muscle function. This gradation of load accelerates muscle adaptation and reduces the time it takes to achieve the desired technical result.

[0082] Thus, experimental and empirical data confirm the achievement of the stated technical result—increased training effectiveness, objectively reflected in a reduction in the time required to achieve results. The combination of active training using a three-stage formula with biofeedback, passive stimulation with an individually selected microtrainer, and a personalized approach creates a synergistic effect that is not immediately apparent to the specialist and is not achieved by known analogs or prototypes.

Claims

1. A method for training the pelvic floor muscles of a woman, including an initial and final examination to assess the condition of the muscles, as well as an individual selection of a training course containing active and passive parts, based on the examination data, in which the active part of the course is carried out using a software and hardware device with biofeedback (BFB), three stages of exercises are performed in strict sequence: - carry out cyclic tonic tension and relaxation of the entire muscle group; - then separate forceful tension and relaxation are carried out alternately in the front and back muscle groups; - and then carry out separate, controlled maintenance of tension and relaxation, alternately, of the anterior and posterior groups of pelvic floor muscles; After which, the passive part of the course is carried out by inserting into the vagina and wearing daily a selected egg-shaped vaginal microtrainer, while the active and passive parts are alternated, and the parameters of the course, including the size of the microtrainer, are adjusted based on the data obtained using biofeedback at the stage of force tension and the stage of separate controlled maintenance of tension and relaxation of the pelvic floor muscles of the active part.

2. The method according to paragraph 1, characterized in that the examinations are carried out both intravaginally, that is, with the installation of sensors or devices in the vagina, and non-intravaginally, that is, without the installation of sensors or devices in the vagina.

3. The method according to paragraph 1, characterized in that the selection of training is carried out both by a specialist and using the Pelvic-Fit device.

4. The method according to paragraph 1, characterized in that the selection of the micro-trainer is carried out by a specialist.

5. The method according to paragraph 1, characterized in that the passive part of the course is carried out by installing in the vagina and daily wearing a selected vaginal microtrainer of an egg-shaped form of one of three sizes - small 1x1.5 cm, medium 1.3x2 cm or large 1.5x2.5 cm.