The Sunmaster 600W Digital Hobby ballast has variable dimming and power boost to support the complete growth cycle. Dynamic high frequency control, 250W, 400W, 600W and 660W (power boost), with soft start-up technology and intelligent ignition for power surge protection.Sunmaster 600W Digital Hobby ballast is silent running, low temperature operation, with circuit safety protection  – compatible with HPS, MH and Dual Spectrum lamps.