PCT No. PCT/DE97/01934 Sec. 371 Date Jul. 14, 1998 Sec. 102(e) Date Jul. 14, 1998 PCT Filed Aug. 29, 1997 PCT Pub. No. WO98/21554 PCT Pub. Date May 22, 1998Known devices for measuring the mass of a flowing medium, or flow rate meters, have a measurement element accommodated in a measurement stub, and a flow rectifier with a grid is provided upstream of the measurement element. For easy production and assembly and accurate alignment of a grid (21) with a flow rectifier (20) of the device (1), the grid (21) has integrally formed-on spring elements (30), which deform elastically when the flow rectifier (20) is installed so that by their spring force, in combination with a detent connection (33, 35) provided on the flow rectifier (20), they durably retain the flow rectifier (20) and the grid (21). The device is intended for measuring the mass of a flowing medium, especially for measuring the flow rate of air aspirated by internal combustion engines.