Gas Vent Pipe; Type Type B Gas Vent, Double Wall, Round; Size 4 Inch Diameter; Length 6 Inch; Material Thickness 0.018 Inch (Outer), 0.012 Inch (Inner); Material G90 Galvanized Steel (Outer), Aluminum (Inner); Weight 0.88 Pound; Inclusions/Features Locking Band; Applicable Standard UL; Outer Diameter 4.5 Inch