Duluth Forge Vent Free Dual Fuel Set-18 in. Stacked Remote Control Gas logs, Red Oak 30,000 maximum BTU heats up to 1,100 square feet of living space Operates on natural gas or liquid propane Minimum firebox size required: 20H x 29"W in front (22W at rear) x 13"D U-Burner chassis design, with black powder coating, provides two rows of flames to create a realistic fire Remote controlled unit features O.D.S. (Oxygen Depletion Sensor) safety assurance with automatic shut-off function