GE, LU150/MED/CP, 150W Lucolux Clear High Pressure Sodium Lamp, Medium Base, MOL 5.75", 24,000+ Hour Life, 16000 Lumens, 2000 Kelvin Color Temperature, CRI=22, B17 Bulb Shape, ANSI Ballast Type S55, 90% @ 50% Of Life Lumen Maintenance, Universal Burn Position, For Open Or Enclosed Fixtures.