Philips Master 3100K GreenPower Elite Agro CMH Lamp, 315 Watt, T-12 Incredibly high 1.95 PPF (photosynthetic photon flux) per watt per second light source 3100k Color Temperature, High 92 CRI, 33,000 Initial Lumens (105Lm/W). Run-Up Time 90% (Max) - 1.5 min High 90% lumen maintenance at 8,000 hr / High 85% PPF maintenance at 20,000 hr Design feature and benefit: provides a compact and efficient metal halide solution for the horticulture market Bulb must be used in a low frequency ballast !! The existing ANSI C182 LCD for the 315W lamp requires that lamps must be operated on a low-frequency square-wave (LFSW) ballast and the starting current limits are minimum 4.1 amps (RMS) and maximum 5.3 amps (RMS)