30"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 31.75"w x 13.75"h] 10in diameter actual front end outer dimensions

actual front end outer dimensions are approximately 27 5/8" width X 28 5/8" height

actual front end outer dimensions are approximately 36 5/8" width X 22 5/8" height

only measure the "hole" in the wall/duct

+ Product Details Size – 18"w X 12"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 18 5/8" width X 12 5/8" height -

30"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 31.75"w x 13.75"h] 10in diameter actual front end outer dimensions+ Product Details Size 30"w X 12"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 31. 75" Width X 13. 75" Height Weather and Pest Proof These louvers are especially designed to prevent water from entering your home, and with a built in back 1 2" mesh they also protect you from annoying rodents like mice, rats, birds, and squirrels High Quality Aluminum The premium durable aluminum will never rust and it will never