Roller shutter comprising an apron guided on either side by a slide, and able to be wrapped around a tube, the apron consisting of interlinked slats, the top slat being connected to the tube, the roller shutter being equipped with a brake, - the apron comprising a braking slat comprising at least two adjacent active portions (6, 7; 106, 107), of which one is the lower portion (6, 106) and the other is the upper portion (7, 107), which are mounted such that they can move closer to one another when the apron, as it descends, encounters an obstacle or a stop, - the brake being a mechanical brake which comprises a control means which is able to sense the two active portions (6, 7; 106, 107) moving closer to one another, and at least one jamming member connected to the apron in vertical translation, - the jamming member comprising at least two jaws (13a, 13b) mounted so as to be able to rotate on a support connected to one of the active portions (6, 7; 106, 107) of the apron, each jaw (13a, 13b) being made to pivot by the movement of the control means which engages with a cam, that is provided on each jaw, in response to the movement of the two active portions of the apron, wherein the jaws pivot so as to project outwards, - each jaw comprising a notched or toothed section which is able to jam against a wall of the slide, - the notched or toothed section of each jaw being located, with respect to the articulation spindle (14, 124), on the opposite side from a cam (16a, 16b), - each cam (16a, 16b) extending transversely, - the control means of the brake comprising a part located in a vertical plane against the edge of the apron, said part comprising two lateral projections (20a, 20b) which come to press on the respective cams (16a, 16b) of the jaws (13a, 13b), characterized in that - the part is held on the upper active portion (7, 107) and comprises a window through which passes the articulation spindle (14, 124) of each jaw, - the support on which each jaw is mounted so as to be able to rotate comprises a body inserted into the end of the lower active portion of the braking slat, this body comprising the spindle on which the jaw is articulated. - the apron comprising a braking slat comprising at least two adjacent active portions (6, 7; 106, 107), of which one is the lower portion (6, 106) and the other is the upper portion (7, 107), which are mounted such that they can move closer to one another when the apron, as it descends, encounters an obstacle or a stop, - the brake being a mechanical brake which comprises a control means which is able to sense the two active portions (6, 7; 106, 107) moving closer to one another, and at least one jamming member connected to the apron in vertical translation, - the jamming member comprising at least two jaws (13a, 13b) mounted so as to be able to rotate on a support connected to one of the active portions (6, 7; 106, 107) of the apron, each jaw (13a, 13b) being made to pivot by the movement of the control means which engages with a cam, that is provided on each jaw, in response to the movement of the two active portions of the apron, wherein the jaws pivot so as to project outwards, - each jaw comprising a notched or toothed section which is able to jam against a wall of the slide, - the notched or toothed section of each jaw being located, with respect to the articulation spindle (14, 124), on the opposite side from a cam (16a, 16b), - each cam (16a, 16b) extending transversely, - the control means of the brake comprising a part located in a vertical plane against the edge of the apron, said part comprising two lateral projections (20a, 20b) which come to press on the respective cams (16a, 16b) of the jaws (13a, 13b), - the part is held on the upper active portion (7, 107) and comprises a window through which passes the articulation spindle (14, 124) of each jaw, - the support on which each jaw is mounted so as to be able to rotate comprises a body inserted into the end of the lower active portion of the braking slat, this body comprising the spindle on which the jaw is articulated.