The Xtrasun BAC400A 400-watt convertible ballast brings flexibility and convenience for your gardening! This ballast operates both metal halide and high pressure sodium lamps and has the ability to operate at either 120 or 240 volts. Use metal halide bulbs for growing, then once plants have started, switch to high pressure sodium lamps for flowering. This ballast features aluminum fins, for added cooling surface, and works well with HydroFarm reflectors and most others. The Xtrasun BAC400A is backed by a 5-year manufacturer warranty. Includes an 8-foot, 120-volt power cord. 240-volt power cord sold separately.