Dyna-Glo IRSS12NGT-2N Infrared Vent Free T-stat Wall Heater. Natural Gas Ready (Fuel conversion not permitted). Infrared Technology works by radiating heat to warm objects first - Similar to the sun. Up to 12,000 BTU's/hr heats up to 300-sq ft; Thermostat control knob automatically maintains your ideal heat level. No electricity required allows for reliable back-up heating incase of an emergency situation. Oxygen depletion sensor will shut down the unit if oxygen were to be depleted.