GYO 400 Watt HPS + MH Grow Light Hood Reflector Digital Ballast Hanger Kit, GYO2022 Fast startup - reaches full brightness in less than 1/4 the time of most magnetic ballasts. Completely silent - no more humming and buzzing. Small, compact design - most electronic models weigh less than 10 pounds compared to 44 pounds for magnetic ballasts Longer bulb life - lumen output loss over time is dramatically less than with magnetic ballasts. Electronic ballasts can light both MH and HPS lamps.