This Sunmaster 400v 600W HPS grow lamp emits both red spectrum and enough blue spectrum light to be used as a sole light source throughout all stages of growing. This eliminates the need to buy separate metal halide and HPS bulbs for the vegetative and flowering / fruiting stages of plant growth. Dual spectrum lamps are increasingly becoming a number one choice for growers as more and more are discovering these bulbs do a great job throughout all stages of plant growth. In fact, we supply most of our grow light systems with dual spectrum bulbs, and so far feedback from our customers has been nothing but positive. Sunmaster grow lights in particular are specifically tailored for the horticultural market and are some of the best lamps around for growing purposes. Their range of dual spectrum bulbs are an economic and easy to use solution for growers. Through feedback and our personal experience we CAN recommend using a dual spectrum lamp throughout the entire growth cycle to achieve fantastic results.