24 gauge Powder-Coated Galvanized Steel Hood with Scalloped Corners and Roll-Formed Edges, 18 gauge 5/8" 100% Galvanized Steel Expanded Metal Mesh Made in the USA Outside Mounting Provides Greater Free Air Space 5/8" Mesh - Required for California Only The Black Galvanized Steel chimney cover 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. Made with a 24 gauge galvanized steel hood with scalloped corners and roll-formed edges, 18 gauge 5/8" expanded galvanized steel mesh for California & Oregon, 14 gauge galvanized steel base.