The Spectralux? Metal Halide (MH) have a 4,200?K color temperature. These lamps emits in the bluish and green regions of the light spectrum with good spectral distribution. Stimulates plant growth more efficiently than any other light source. They are engineered to be compatible with both magnetic and electronic ballasts. Spectralux? lamps are optimized for use with Sun System? brand ballasts and reflectors. The Spectralux? lamps are high quality, feature robust construction and have excellent reliability. Universal burn position.