The HRD-JRPIN1 Junior Pin is a Male Mounting Plate with screws for the SpaceBox LED is an optional accessory designed to rig straight into a Junior Receiver grid clamp. So, instead of using the four suspension chains on the SpaceBox LED, you have the option of using the Junior Pin Plate instead. This allows the SpaceBox LED to be mounted right up against the pipe grid, giving you extra height clearance.