This glide mounted rack shelf features a adjustable rail system that attaches to the front and rear rails of your rack or rack frame for incredible strength. It can support up to 75 pounds of weight yet weighs 12 pounds itself and only occupies a single unit of space. Also available with venting for maximum air flow that helps keep your equipment cool. When mounted upside down this shelf becomes a 1U drawer if desired. Mounting screws are included.