mr. heater, mr heater big buddy, portable heater, indoor propane heater, portable propane heaters, propane heater, portable space heater, mr heater portable buddy 4,000- to 18,000-BTU radiant heater for spaces up to 450 square feet. Approved for indoor/outdoor use; clean-burning; nearly 100-percent efficient When operating the heater at altitudes over 7,000 FT above sea level the heater may shut off. Auto shut-off if tipped over, if pilot light goes out, or if detects low oxygen levels Low, medium and high heat level control knob for steady temperatures; connects to propane tank propane tank not included