600w ballasts for grow lights can operate up to 600w high pressure sodium (HPS), metal halide (MH), Dual Arc, and Conversion grow lamps, depending on their specifications. Digital (electronic) ballasts use circuitry in place of transformers, capacitors, and ignitors that traditional magnetic ballasts have. Magnetic ballasts often run warmer than electronic ballasts, and they require slightly more power (approximately 5% more wattage) to drive the same wattage bulb as an electronic ballast, yet they are often less expensive in terms of upfront cost. Another added benefit of electronic ballasts is that they can often be dimmed down to less wattage e.g., a 600w ballast can be dimmed down to run 600w or 400w bulbs. Check specific ballast for this feature.