Earth Worth 1000W Electronic Digital Ballast For HPS or MH 1000 Watt Grow Bulbs - Dependable and Affordable! Rated Power: 1000 watts (High efficiency) Bulb Compatibility: 1000 watts High Pressure Sodium Lamps OR Metal Halide Lamps Quiet Operation Reduces Operating Noise Interior Fan saves Energy and Lowers Operating Cost Specified Frequency: 50/60Hz