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.