Maximize the air and sound performance of your Broan ventilation fan or range hood using one of our wide variety of ducting accessories.Overall size showing on the surface is 9 in square with a 5-1/2 in hood and a 1-1/4 in long attachment collar for 6 in 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 outsideWall cap is made of 22 ga CRCQ steel construction with a 0.025 natural aluminum finish for durability and long life