8" DuraVent DuraPlus Stainless Steel Tee with Cover 8DP-TSS This tee is used for through-the-wall chimney installations. The tee clean-out cap is removable for easy chimney cleaning or inspection. Wall straps a wall thimble and a tee support must be installed with the tee as directed. Tees have 1" insulating blanket. Ventilation air for chimney must be drawn from outdoors. 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.