Product details:

The Shelter Single Flue Black Galvanized Steel Chimney Cap is the durable and economic choice for chimneys in most regions. The outside mounting design provides maximum free air space and better draft while the attractive powder coat finish helps it stand up to the elements. This single flue chimney cover is made with a 24 gauge galvanized steel hood with scalloped corners, 18 gauge 3/4 in. expanded galvanized steel mesh, 14 gauge galvanized steel base and slotted hex-head bolts.Designed & Engineered to Bolt-On to Existing Clay Flue Tile
Fits outside tile dimensions 7 " x 16 " to 9 " x 18 "
Outside mounting design provides maximum free air space and better draft while attractive powder coat finish helps it stand up to the elements