Features continuous electronic ignition and adjustable heat output from 25,000 to 40,000 Btu an hour for buildings from 2,000 to 4,000 cu. ft. High-output fan for better circulation of heated air. Automatic electronic ignition will not take place unless heater is plugged in. Propane flow stops if heater is accidentally unplugged. Can be operated for hours (at low setting) from a standard 20-lb. tank. Powder-coated finish. Patent #5,553,220 AGA and CGA Certified.