Abstract: A cage in a piece of computing equipment with a rectangular opening in a surface of that equipment is adapted for having inserted therewithin a piece of peripheral equipment with a rectangular front plate and with first and second guide rails located along its first and second sides, respectively, each having a circular hole of a prescribed diameter therethrough at prescribed distance from the front plate. The cage has first and second lead rails on first and second opposed sides thereof with which lead rails the first and second guide rails respectively engage. The lead rails each having a circular hole of the prescribed diameter therethrough to align with the hole in the guide rail it engages, when the inserted peripheral equipment is fully inserted. The cage has a third side extending between edges of its first and second sides, which third side has first and second holes therethrough of said prescribed diameter.