The Superior unique, clean burning design provides 99% heating efficiency, allowing you to operate the logs vent-free with the fireplace damper closed. With no venting required, there is no heat loss up the chimney. Plus heating with Superior gas logs means you'll never again be left in the cold with wet logs or without heat during a power outage. Includes: Boulder Mountain Log Set Only Features: Model #: LBG18BM. LOGS ONLY: Boulder Mountain Log Set. BTU: 19,000 - 32,000. Fuel Type: Gas. View Style: Front View. Venting Type: Vent-Free. Log Material: Cast Refractory. Control Type: Millivolt, Thermostat, Variable and Electronic. For use with: BGE18 Vent Free Burner System by Superior Fireplaces. Warranty: 3 Year Limited Warranty. Specifications: Log Size: 18". Minimum Fireplace Dimensions: 26" (W) x 14.5" (D) x 17" (H). Burner is shown in image, however not included in this product.