A Dell Rapid Rail is a Dell OEM Specific rail kit. This rail kit is designed to be installed into a Square Hole 4Post Rack or Enclosure. What makes this rail unique is that this rail has hooks on each end that allow it to be installed into a square hole without the use of tools or screws. This is also known as a Tool-Less Install. The Dell Rapid Rail typically has a mounting depth of 28″ to 29 1/8″. It is important to note that this kit is not solely for use in a Dell Rack. This kit will work in most 4Post racks that have square holes and meets the depth requirements of the rail kit.