Indoor safe propane heater. Radiant heater provides safe heat for chilly garages, tents, patios, porches, cabins, etc. It has been designed and approved also for indoor use. Automatic low-oxygen shutoff system. Uses 1 lb. or 20 lb. propane cylinder with optional hose connection model No. F273701 (5') (SKU 424633) or F273702 (12') (SKU 425435). Free standing or wall mount. Quiet, odor-free, lightweight, portable. Easy-to-carry 4000 and 9000 BTU settings. Heats up to 250 sq. ft. Fuel cylinders not included. Low oxygen sensor prohibits use at altitude above 7000'.