NorWesco 7-3/4" Galvanized Steel Grey Static Roof Mount Attic Vent

38" square roof vent. Galvanized steel construction. 7-3/4" baffle diameter opening. 17" x 17" base plate. 1/8" mesh screen. 38 sq. in. of net free area per vent. Designed for composition or shake roofs. Large base offers added protection and ease of installation. All parts are fastened by rivets.