Digital ballast. 1000W, 600W, 500W and 400W MH/HPS compatible , ... inside The features of the Welthink series Grow light ballast,digital ballast.Run for HPS and MH lamps both.High ... between -15%~15% of rating voltageProtection functions: Open circuit and short circuit protection functions available.Easy installationEasy to hang the lamp ... UL,CUL, CE,TUV, listed 120-240V,1000W,600W,400W, digital ballast