Duluth Forge Vent Free Dual Fuel Set-24 in. Berkshire Stacked Remote Control Gas logs, Oak 33,000 maximum BTU heats up to 1,300 square feet of living space Patented dual fuel technology operates off natural gas or liquid propane Minimum firebox size required: 20H x 28W in front (23W at rear) x 15D Remote controlled unit features O.D.S. (Oxygen Depletion Sensor) safety assurance with automatic shut-off function Thermostat remote control and LCD display screen