A box comprising at least one portion that is closed by a movable cover and that contains an electronic detection circuit for detecting opening of the cover, the cover being provided with means for locking it in the closed position, said means comprising a screw that is mounted on the cover to pivot between a locking position and an unlocking position, and having an end provided with at least one tooth for meshing with teeth of a code wheel mounted to pivot in register with pads of the detection circuit, wherein the screw is mounted so that said end of the screw presents positioning with radial clearance relative to the box in such a manner that the pivoting of the code wheel has an amplitude that depends on the positioning of said end as authorized by the radial clearance.