Broan 641 Wall Cap for 6" Round Duct for Range Hoods and Bath Ventilation Fans Overall size showing on the surface is 9" square with a 5-1/2" hood and a 1-1/4" long attachment collar for 6" round ductwork (NOT for use with dryer venting) Equipped with a spring-loaded backdraft damper and bird screen to keep nests and small animals on the outside Wall cap is made of 22 gauge CRCQ steel construction with a .025 natural aluminum finish for durability and long life Sold as 1 to a carton