6" DuraVent DuraLiner Oval Spacer 6DLR-S 6" DuraLiner Oval Spacer is used to maintain a 1" clearance with flex sections of DuraLiner. Diameter: 6" Thickness: 3 1/4" Sturdy construction for long-lasting durability Use to maintain a 1†clearance with flex sections of DuraLiner .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.