The Philips Master Color CDM (CMH) Bulb, 315 Watts - 4,200 K is one of the best lamps out there for hobby and commercial growers alike. It gives your plants the spectrum of light they need for explosive growth, with a super crisp white light for veg-flower growing. In terms of output, spectrum, efficiency, and reliability, this bulb cannot be beat. Here are all the reasons we love this lamp: \nBenefits Of The Philips Master Color CMH Bulb, 315 Watts - 4,200K \nThe Philips Master Color CDM (CMH) Bulb, 315 Watts - 4,200 K puts out an ultra-high 1.95 PPF per watt/second light source. This 4200K is great for full cycle growing, and features a high 92 CRI with 33,000 initial lumens! The bulb maintains its output incredibly efficiently over its life, with 90% lumen maintenance at 8,000 hours and 85% maintenance at 20,000 hours. \nThis bulb is built with a double glass jacketed bulb, which can be used for open fixture use or enclosed fixture It's built with a Bi-pin lamp base is compatible with all Sun System® LEC® Brand Technology Fixtures. \nWe recommend keeping it in the family, using only Philips brand electronic ballasts. They are designed to operate together at max capacity in a sustainable manner long term. If you don't stick with Philips ballasts, you'll likely see a decrease in lamp performance and a shortened life span. \nAdditional Features Of Philips Master Color 315w 4,200K CMH Bulb \nUnbeatable PPF (Photosynthetic Photon Flux) 1.9 umols/s for intense output your plants will love \nSuperior lumen/PPF maintenance of 90% at 8,000 hours, getting you your moneys worth from this bulb \nLong life 20,000-hour rated average life, saving you money on bulb changeouts and cutting back on your workload \nSuitable for use in open fixtures and closed fixtures with the double jacketed bulb \nHigher growth light compared to 400W HPS lamps \n93% ballast efficiency can provide substantial energy savings \nIncreased time between re-lamping cycles when compared to standard metal halide lamps