8" DuraVent DuraPlus Galvalume 15-Degree Elbow Kit 8DP-E15 This 15 ° elbow kit is used for offsets around obstructions such as rafters ridgepoles or joists. May have two pairs of elbows if needed. Elbows swivel 360 ° at base (angles are not adjustable). A pair of elbows is required to return an offset chimney back to vertical. Kit includes: (2) elbows and one elbow strap. Use when air-cooled chimney is required Free-floating inner 430-alloy liner maintains structural integrity in chimney fires 2" clearance to combustibles Outer diameter is 4" larger than inner diameter Triple-wall chimney For uses with wood stoves fireplaces furnaces boilers stoves ranges water heaters or other appliances fueled by wood oil coal or gas Clean smooth exterior finish .016†430 stainless steel outer wall or .018†galvanized steel outer wall. .018†aluminized steel intermediate liner. .016†430 stainless steel inner liner. Insulated layers plus ventilated air space. Locks tightly with a precision twist-lock connection.