GE HR175DX39/LTP. It's a 175 watt, WH glass ED28 Mercury bulb with a mogul base. The bulb provides 7800 lumens and has a color temperature: 3900 Kelvins. With a CRI: 46, and an MOL: 8.31". The bulb is non-dimmable, with a rated life of 20000 hours. Item Notes: For use with H39 ballasts.