Mounts and locks on outside lip of any Magliner Shelf. This is a great accessory to put your Sharpie pens, tools, gaffer and photo tapes. Part No: MAG-UB48 Material: Steel Color: Black Max. Capacity: 40 lbs. Weight: 10 lbs. Dimensions: L48” x W4” x H5" (ID L46” x W3 3/4” x H5”) Requirements: Mag Senior Top Shelf (18” or 24”) Conflicts: Mag Junior Top Shelf (18” or 24”), Mag 2-Space Roller Sliding Drawer with Lock, Mag Keyboard Tray Suggestions: Mag Grip/Light Caddy, Mag C-Stand Holder (4), Mag C-Stand Holder (2)