The Solarmax Veg Conversion lamps are Metal Halide bulbs designed to work in a High Pressure Sodium ballast. The advantage of a Metal Halide lamp in the growth phase of a plant is increased vegetative growth as well as reduced internode length. The disadvantage of Conversion lamps is that they are inefficient compared to their standard counterparts. The 400W MH conversion lamp produces 32,000 lumens and is 7200 Kelvin in color temperature. We do not suggest using these lamps in digital ballast, please use standard lamp types.