CAD/3D Files: Firebox 30 Firebox 30 Liquid Propane/Natural Gas - Electronic Ignition System (73,500 BTU) Firebox 30 Liquid Propane/Natural Gas - Match Lit (60,000 BTU) Firebox 30 Liquid Propane/Natural Gas - Match Lit with Flame Supervision Device (73,500 BTU)