Exterior Material: Steel Burning Area Material: Stainless Steel Fuel Type: Propane; Natural Gas (Natural gas conversion kit is NOT included with fire pit due to regulation reasons. Customers need to buy it separately for conversion.) BTU Output: 50000 BTU Compatible Filler Type: Lava Rocks Durability: Rust Resistant; Heat Resistant Note: Natural gas conversion kit is NOT included with fire pit due to regulation reasons. Customers need to buy it separately for conversion.