The Monorail 300W 24V Sloped Ceiling Surface Mount Transformer by Edge Lighting Monorail 300W 24V sloped ceiling surface mount transformer mounts to a standard 4 inch square electrical box with round plaster ring or octagon electrical box (not included). The transformer converts standard 120V line voltage to safe-to-touch 24V low voltage power, and is protected by fast-acting circuit breakers. For use with Halogen or LED lamp sources, maximum 300W load. Dimmable with a standard magnetic low voltage dimmer with halogen lamp sources. For dimming LED visit www.edgelighting.com for the most up-to-date dimmer information. Available in 2, 6, 12, 24, 36, 48, or 96 inch heights. Finish available in satin nickel, polished nickel, or antique bronze. ETL listed.