Cool Grow Lamps emit light from 5,500° K, imitating the natural look of daylight. They are an ideal light source for the seedling and vegetative stages of plant growth, while still emitting a wide spectral distribution. Sunmaster® Cool Metal Halide Lamps surpass many other HID sources in PAR watts–the most objective measurement of total light energy available for photosynthesis. Designed for optimal performance on electronic ballasts.