These units power and control HPS (High Pressure Sodium) and MH (Metal Halide) lights. Lamps cannot function without these units. We stock a variety of types of ballasts. All run both HPS and MH bulbs. We also stock a wide range of reflectors for use with HPS or Metal Halide ballasts. These help create better reflection from bulbs' light by promoting rays to reflect towards the growing area. These reflectors can be used without ballasts if being used with Envirolights or any self ballasted lamp with an E40 fitting.