24-gauge single-piece galvanized steel hood. 18-gauge 3/4" expanded galvanized steel mesh. Black powder-coated paint finish. Stainless steel mounting brackets. Quick and easy installation (with only a screwdriver). Keeps out birds, squirrels, leaves, and debris. Protects flue from moisture. 1 cap fits several flue tile sizes: 13" x 13", 13" x 18", 9" x 18", 12" x 16", 8" x 17" Oval, 10" x 17" Oval, 13" x 17" Oval.