... 3 different wattage bulbsKey Word: Electronic Ballast, Dimmable Electronic Ballast, Grow Light Ballast 400W, Hydroponic grow ballast 400w, electronic ballast 400w, 110V, UL Listed1) ... crest factor: <1.5 7) Max. Lamp distance from ballast: 15m/49ft 8) Ambient temperature: -25 ~ +50 Centigrade ... A) Low power loss B) High power factor C) High lighting efficiency 2) Perfect protection and monitoring ...