ViaVolt HPS (High Pressure Sodium) to MH (Metal Halide) Conversion Grow Light gives the grower the ability to have the MH blue spectrum while using HPS ballast. Grow lights have an effective spectral distribution for stimulating vegetative plant growth. Metal Halide Grow Lights emit light most heavily in the blue wavelengths of the electromagnetic spectrum. Metal Halide bulbs stimulate vegetative growth in plants more efficiently than other light sources designed for growing plants. It is best to use MH Grow Lights in addition to or cycled with High Pressure Sodium grow lights. 58,000 Lumens, 7,200K, T25 Lamp.