SYLVANIA 64452 - 400 Watt - BT37 - SUPER METALARC - Metal Halide - Protected Arc Tube - 3600K - Coated - Base Up Burn - MS400/C/BU-ONLY 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 Sylvania BT37 bulb, 400W, Base: E39 Mogul Screw, Rated Life (hours): 20000, Color Temp: 3600K, Luminous Flux (LM): 42000