These Philips lamps feature superior color quality and very crisp white light. Incredibly high 1.95 PPF (photosynthetic photon flux) per watt per second light source. 3,100øK Green Power or 4,200øK color temperature lamps available. High 92 CRI, 33,000 initial lumens (105Lm/W). High 90% lumen maintenance at 8,000 hr/High 85% maintenance at 20,000 hr. Double glass jacketed lamp is rated for either open fixture use (without glass lens) or enclosed fixture use (with glass lens).