GE 10389 - 1000 Watt - BT37 - Multi-Vapor - Pulse Start - Metal Halide - Unprotected Arc Tube - 3900K - Mogul Base - ANSI M141 - Universal Burn - MVR1000U/BT37/PA 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 GE BT37 bulb, 1000W, Base: E39 Mogul Screw, Rated Life (hours): , Color Temp: 3900K, Luminous Flux (LM):