Mhu50-50,000 btu, big maxx natural gas unit heater, 50,000 btu per hour, heats up to 1250 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, 3" flue size for vertical vent & 4" for horizontal, category 1 vertical: category 3 horizontal venting.