GE 45664 - 400 Watt - ED37 - PulseArc Multi-Vapor - Pulse Start - Metal Halide - Unprotected Arc Tube - 4000K - Mogul Base - ANSI M135 or M157 - Vertical Base Up Burn - MVR400/VBU/HO/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 ED37 bulb, 350W, Base: E39 Mogul Screw, Rated Life (hours): 20000, Color Temp: 3700K, Luminous Flux (LM):