For use with Vented/Vent-Free Slope Glaze Burners For 32 in Minimum Firebox Size Includes Burner amp Valve All burner choices are 25 000 Btus These burners are vent free systems that can convert to vented systems by opening flue damper NOTE VENT FREE APPLICATIONS ARE RATED FOR A MAXIMUM ELEVATION OF 3500 FEET - Buy Now or get More Info on Empire Fireplaces - Click Here To Order