GE, LU100/MED/CP, 100W, Lucolux High Pressure Sodium Lamp, Medium Base, MOL= 5.5", 24,000+ Hour Life, 9500 Lumens, 2000 Kelvin Color Temperature, CRI=22 , B17 Bulb Shape, 90% @ 50% Of Life Lumen Maintenance, Universal Burn Position, For Open Or Enclosed Fixtures.