8" X 48" DuraVent DuraLiner Oval Rigid Pipe 8DLR-48O 8" X 48" DuraLiner Oval Rigid Pipe is used to reline a masonry chimney with 0/0 clearance. Factory-insulated. Built-in pre-drilled fittings for riveting joints. 304 stainless steel inner and aluminized steel outer. Diameter: 8" Length: 48" 304 stainless steel inner and aluminized steel outer .016†304 stainless steel inner liner. Rigid relining pipe: double-walled with 304 stainless steel inner and galvalume outer. Factory insulated between inner and outer walls.