The invention concerns a device with a curtain which can be rolled up and unrolled between a shut position and an open position, whereby this curtain (1) comprises a belt (2,3) on each of its faces, whereby each belt (2,3) has successive teeth (5,6) in the longitudinal direction, whereby these belts (2,3) are situated opposite one another in such a way that they can mesh when the curtain (1) is being rolled up. At least one of these belts (2,3) comprises teeth (5,6) having at least one recess (8,9) in which at least one protruding part (10,11) of the teeth (5,6) of the other belt (2,3) can engage in such a way that the two belts (2,3) can mesh and such that one of these belts (2,3) can push the other belt (2,3) in their longitudinal directions.