MH18B Portable Propane Heater, Red 4, 000, 9, 000, or 18, 000 BTU per hour Heats up to 450 sq. ft. Hi-Med-Low heat settings Automatic low oxygen shut-off system ODS and accidental tip-over safety shut-off THE USE OF UN-AUTHORIZED ACCESSORIES/ATTACHMENTS WITH THIS HEATER ARE EXPRESSLY PROHIBITED, MAY CAUSE SERIOUS INJURY, AND WILL VOID THE.