Selkirk Metalbestos 6T-IWT 6-Inch Stainless Steel Insulated Wall Thimble Installs quickly and eliminates the need for using individual firestops The round shielding acts as a radiation shield and provides the required 2-Inch air space clearance to combustibles The two sections telescope to accommodate 6-Inch to 11-Inch wall thickness Opening of face plate is 8-inches in diameter 6-Inch chimney pipe has an outside diameter of 8-inches; not to be installed through the wall of a home