This DuraLiner 6 Inch x 36 Inch Chimney Relining Oval 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. Made of 304 stainless steel in the inner wall and aluminized steel on the outer wall. Features: Type: Rigid Pipe. Shape: Oval. Double Wall Construction. Inner Material: 304 Stainless Steel. Outer Material: Aluminized Steel. Specifications: Overall Dimensions: 36" (L). Inner Diameter: 6".