Virtual Sun VS1000WDBD 1,000-Watt Dimmable HP/HPS Digital Grow Light Ballast Drives high pressure sodium and metal halide bulbs to peak performance Dimming switch for absolute control over the amount of light your crops receive Uses 5-12% less energy than magnetic ballasts Cleaner & constant power to bulbs, maximizing life and crop yield Anodized, extruded aluminum housing for cooler running temperatures