UltraGrow Premium Switchable MH/HPS Ballasts provide reliable performance at a value price and are fully UL Listed. Easily switch between growth promoting metal halide to flower producing sodium by flicking a switch and inserting the appropriate 1000 watt lamp into any compatible reflector (not included). Powder coated aluminum fins provide extra cooling effectiveness. Dual voltage capable and compatible with most major 1000 watt metal halide or high pressure sodium lamps. Rubber feet reduce noise and vibration.