Quality engineered and manufactured to maintain a consistent draft on a wide range of oil and gas fired heating equipment. May be used with chimney vented or power vented heating equipment. For fan assisted gas, oil or solid fuel applications with vent diameters from 4''-10'', choose the DC4 thru DC10. For LP and natural gas applications with vent diameters from 4 to 10 in, choose the DC4G thru DC10G.