Overall sizing is 12-3/4 wide x 5-5/8 high. Duct fitting protrudes 4-7/8 from back of cap to allow proper fit to the 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 24 gauge CRCQ steel construction with a black electrically-bonded epoxy finish for durability and long life.