MHU125-125,000 BTU, Big Maxx Natural Gas Unit Heater, Heats Up To 2000 SQFT, Spark Ignition Features Self-Diagnostic Control Module, Includes 2 Angle Brackets For Ceiling Mount, Ships As Natural Gas, Includes Ng To LP Conversion Kit, 4" Flue Size, Category 1 Vertical: Category 3 Horizontal Venting, 1/2' Gas Connection, Built-In Electric High Velocity Fan To Pull Cool Air Into The Rear Of The Heater & Over A Heat Exchanger, Forcing Hot Air Into The Surrounding Area, Require 115V AC Power & Can Operate Using Propane LP Or NG, Proper Venting Is Required & Is Sold Separately.