Eclipse LED digital ballasts are more efficient, quieter, cooler, and
softer on the bulb. Digital ballasts do not have any of the usual
transformers, capacitors or igniters; instead these ballasts have
electronic circuitry to do the same job, more efficiently. What might
take a standard coil/magnetic ballast 680-700 watts to fire a standard
600 watt bulb, may only take a digital ballast only 600-620 watts to
fire the same bulb to the same brightness.


http://www.eclipseledcompany.com/Digital_Ballasts.html