Philips Lighting 337139 ED-23 1/2 Standard Mercury Vapor Lamp 100 Watt E39 Mogul Base 4400 Lumens 45 CRI 3950K Cool White HID Bulbs produce high output for their size making them a compact powerful &amp; efficient light source HID Bulbs are used for general lighting, professional lighting fixtures, growing applications HID bulbs put out around 3-5 times greater output (lumens per watt) than traditional halogen bulbs Philips ED23.5 bulb, 100W, Base: E39 Mogul Screw, Rated Life (hours): 15000, Color Temp: 3900K, Luminous Flux (LM): 4200