MHU80-80,000 BTU, Big Maxx Natural Gas Unit Heater, 80,000 BTU Per Hour, Heats Up To 2000 SQDT, 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.