The powerful spectrum of HORTILUX? BLUE is now available in a 600 watt version. 600W BLUE is a metal halide lamp designed to operate on 600W electronic ballasts or core and coil (magnetic) HPS ballasts rated ANSI S106. All 600 watt core and coil (magnetic) ballasts are HPS rated, therefore, the 600W BLUE is a conversion lamp on this system. Please note that there are no 600W Metal Halide core and coil ballast. They do not exist in the general lighting industry. That is why ALL 600W Metal Halide lamps are conversion lamps designed to run on HPS core and coil ballasts. This lamp can be used in the following ways: 1. BLUE all the way through?start to finish: This lamp can be used as a standalone light source which will grow the highest quality natural looking plants throughout all phases of their growth cycles.2. Start with BLUE, finish with SUPER HPS: Growers who prefer to use metal halide for early plant development and then switch to high pressure sodium for flowering and fruit production can also successfully use this product. 600W BLUE allows aggressive vegetative growth using your existing HPS system. Simply switch back to your 600W HPS lamp for flowering and fruit production.3. Mix BLUE with SUPER HPS start to finish: Multi-light systems can combine our HORTILUXTM BLUE along with HORTILUXTM Super HPS lamps for a more balanced spectrum to produce higher yields and quality of plant growth throughout all phases of plant growth. NOTE: This bulb is compatible with the Phantom II 600W ballast (PHB2030), but not with older style Phantoms or the Xtrasun Digitals (XTE600D).