A storage system allows secured attachment in a device, such as a refrigerator, a freezer, a medical cart or the like, having a shelf comprising spaced-apart wire rack ribs. The storage system has a body with top and bottom walls, side walls, a rear wall, and an open front face opposite the rear wall, the top wall having a pair of spaced-apart apertures. A front door, hingedly attached to the body, is sized to fully close the front face when attached thereto. The body is attached to the shelf using a screw and a screw-retaining member, with the screw-retaining member operating to secure the ribs of the shelf between itself and the body. A screw, with its head located inside the body, passes through one of the apertures and is threadingly secured to the screw-retaining member.