A digital or electronic ballast uses solid state electronic circuitry to provide the proper starting and operating electrical conditions to power HPS and Metal Halide bulbs.
Digital ballasts offer dramatic design and performance improvements over magnetic ballasts. Digital ballasts run cooler than magnetic ballasts.
A digital ballast can be smaller and lighter than a comparably-rated magnetic one. A digital ballast is usually quieter than a magnetic one, which produces a line-frequency hum by vibration of the transformer laminations.
The use of digital ballasts will also increase the life span of your bulb because they reduce the level of current flowing through the circuit.
Digital Ballasts allow more light to be put down by your bulb than magnetic ballasts.