These sturdy units mount conveniently into one 19" rack space providing light from two gooseneck incandescent bulbs. A dimmer switch on the front panel allows you to easily adjust the light to exactly the amount desired. The RL-I is powered by a detachable 6" cord with an enclosed 12 VAC power supply inside the AC plug (wall wart). This cord supply is conveniently attached to the rear of the panel by a 2.1 mm barrel connection, allowing fast, reliable operation.