A bellows insert (25) is shown, mountable inside a bellows for a vacuum powered tool and, in the mounted position, effective to locally limit the capacity of the bellows of compression in its longitudinal direction caused by a negative pressure introduced into the bellows. The bellows insert includes an engagement part (26) that has a shape complementary to the inside of the bellows and that, in the mounted position of the bellows insert, fills up some or all of the pleats of the bellows, within a limited area of the circumference of the bellows.