When an extremely hot flame is required, these Meker-type burners form uniform blue cones of intese heat with no backflashes. Onepiece, nickel-plated venturi tube. Die cast, zinc alloy, nickel plated octagonal base. *Note: CFHs and BTU Outputs are figured on: 5 inch Water Column Pressures for Artificial and Natural Burners. 11 inch Water Column Pressures for LP Burners. Inlet OD for all Burners: 5/16" Serrated