GE LU150/MED/LTP. It's a 150 watt, CL glass ED17 High Pressure Sodium bulb with a medium base. The bulb provides 16000 lumens and has a color temperature: 2000 Kelvins. With a CRI: 22, and an MOL: 5.43. The bulb is non-dimmable, with a rated life of 24000 hours. Item Notes: For use with S55 ballasts.