Digital ballast. 1000W, 600W, 500W and 400W MH/HPS compatible , ... the Welthink series Grow light ballast,digital ballast.Run for HPS and MH lamps both.High power factorPF≥0.98Low harmonicGeneral harmonic ... THD≤ 10%High light efficiencyand energy saving.Low ... UL,CUL, CE,TUV, listed 120-240V,1000W,600W,400W, digital ballast