"LL BUILDING PRODUCTS" GAF/MASTER FLOW ROOF VENT Weathered Wood finish Slant back louver Aluminum material resists rust. Fully enclosed hood to help prevent rodent/insect infiltration and leaf/pine needle clogging. Embossed finish hides scratches and resists wear. 12 percent larger flashing with pre-drilled nail holes makes installation easier, helps prevent leaks. 9-7/8" opening; 18" x 201/2 flashing dimension. 60 sq. in. of net free ventilating area per vent. Dade County Approved. Florida Building Code (FBC) Approved for specified SKUs.