Abstract: A closure system for a cage containing laboratory animals, where in an upper edge of the base of the cage an U-shaped housing towards the outside of the edge hosts a gasket having a lip projecting out of the upper edge, and s bending in contact with a side rim of the top, the side rim overlapping the upper edge, and comprising at least two latches, connected on one side to the base, and having a bending line with a smaller thickness, and a projecting hook at the opposite side, to be restrained in a slot in the top, so that in operation the latch bends in the bending line and the projecting hook can be engaged to or disengaged from the slot.