THUNDER (TM) TBF400 Horticulture Hydroponic 400 - Watt HPS MH Digital Dimmable Electronic Ballast for Grow Lights - (CE Certified and UL Listed) - 5 Year Manufacturer Warranty Lamp Dimming Option From 50% / 75% / 100% Extremely Efficient with 99.9% Efficiency Microchip Controller prevents hot starts in case of power outages Soft Start Technology is designed to prolong a lamp;s life usage 5 Year Warranty card from Thunder for each unit