This 012635 Black Metal Roof Vent Cap is designed for use with range hood and bath fan exhaust. It is 26 gauge galvanized steel with a black powder coat finish. This 4-inch version includes a removable 1/4 x 1/4 inch screen and a removable backdraft flapper. Builder’s Best black metal roof caps begin with galvanized steel which has some corrosion protection. The high performance polyester powder coating shows very little corrosion when subjected to the ASTM B117. These roof caps have been tested for 480 hours (20 days) with a sodium chloride (salt) solution to accelerate a corrosion process. (ASTM B117 tests conducted by a third party lab.) These roof caps performed much better than the leading brand (painted steel) and a foreign brand (painted galvanized). The 012633 Black Metal Roof Vent Caps are built in the USA by Builder’s Best, Inc.