Lomanco Static Roof Vents unique design provides maximum weather protection. Offers a large nailing flange for ease of installation. Features bird-proof design, a weather tight seamed collar, and a high profile and rolled flange on the vent stack for superior weather protection and circulation. Prevents roof discoloration Large nailing flange 3 sided louver for greater air flow All-aluminum rust-free construction Fits all pitched roofs Bird-proof design Weather tight seamed collar. Specifications: Opening Size (in.): 8 Overall Size (in.): 16" x 20-5/16" x 5 Black.