This DuraLiner 6 Inch x 1 Foot Chimney Relining Double Wall Round Rigid Pipe efficiently helps venting of heating appliances while protecting masonry chimneys from the damaging effects of flue gas. Use to reline masonry chimney with 0/0 clearance. Factory-insulated. Built-in, pre-drilled fittings for riveting joints. 304 stainless steel inner and aluminized steel outer. Features: Type: Rigid Pipe. Shape: Round. Double Wall Construction. Inner Material: 304 Stainless Steel. Outer Material: Aluminized Steel. Specifications: Overall Dimensions: 12" (L) x 6" (W). Inner Diameter: 6".