This classic black roof cap com includes a handy exhaust vent adaptor to fit 3" or 4" ductwork. Includes built-in damper to prevent backdraft. Fits all pitched roofs.Includes 1 roof louver (black) AND adaptor plate with damper Roof Louver Features:* Fits all pitched roofs.* Weather-tight seamed collar.* Prevents roof discoloration.* Embossed painted finish for added strength, extended paint life, durability, and blending appearance with shingles. * Bird-proof.* Large nailing flange.• Dade County Approved #01-0614.05 Adaptor Plate Features:* Exhaust vent adapter fits 3" or 4" flexible duct.* Designed for use with bathroom exhaust fans* Exhausts household moisture.* Tested for all climates.* Built in damper prevents backdraft.* Works with any roof system.* Ideal for new construction.* Solution for existing homes.* 10" nailing flange.NOTE: DAMPER ASSEMBLY WILL REDUCE DUCT SIZE TO 3"Specifications:Vent overall dimensions - 12 3/16" X 17 3/4" X 4"Adaptor plate overall dimensions - 10" X 10" X 3 1/4"