... HPSMH compatible No fans inside, digital electronic ballast 1000w. Welthink WEX120 and WEX230 digital ballast are designed specially for hydroponics, greenhouse, horticulture ... optional. The features of the Welthink series Grow light ballast,digital ballast.Run for HPS and MH lamps both.High power factorPF ... are available . UL,CUL,CE,TUV certificated digital electronic ballast 1000w,600w,400w,250w