The Round Stainless Steel Chimney Adapter is used to mount an ENERVEX chimney fan to round stainless steel chimney pipe, including solid-pack and Class A insulated chimney systems. This adapter provides a secure transition between the chimney pipe and fan, helping ensure proper fit and stable installation at the top of the chimney. Choose this adapter when connecting to standard round stainless or insulated chimney pipe, not air-cooled chimney pipe.