This Vault Drawer mounts to the underside of any shelf. It provides 11.5" w x 12" d x 2" h worth of previously unused space. Ideal for a variety of loose valuables and documents. The Wire form frame slides over any shelf up to 1" thick. The frame's retaining bar butts up against the tray's molded lip to keep the user from pulling the drawer out to far and spilling its contents.