Gas Vent Pipe; Type Double Wall, Round, Adjustable Length, Gas Vent; Applicable Standard UL 441, CUL, NFPA 54; Size 12"; Length 18"; End Type Twist Lock x Twist Lock; Material Thickness 0.018" Inner Wall, 0.024" Outer Wall; Material Aluminum Alloy Inner Wall, G90 Galvanized Steel Outer Wall; Temperature Rating 530 Deg F; Insulation Supplied Yes; Inclusions/Features Integral, Annular Insulating Air Space; Adjustable Length 3" to 8"; Minimum Clearance 1"; Air Insulated Pipe Thickness 1/2"; Assembled Length 1.5"; Application Gas Furnace, Heaters, Fireplace, Boiler; Warranty 1 Year Limited