Device with windable curtain

A device with a curtain which can be rolled up and unrolled between a shut position and an open position, said curtain (1) having lateral edges and a first and a second face opposite to each other, the curtain comprising a belt (2,3) with a longitudinal direction on each of its faces, wherein each belt (2,3) has successive teeth (5,6) extending along said longitudinal direction, said belts (2,3) being situated opposite one another in such a way that they can mesh when the curtain (1) is being rolled up, wherein at least one of these belts (2,3) comprises teeth (5,6) having at least one recess (8,9) forming an undercut 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 a longitudinal direction, wherein said protruding part (10,11) of each tooth (5,6) hangs over the recess (8,9) forming said undercut defined by said protruding part of said each tooth in the longitudinal direction of the belts (2, 3).