22"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 23.75"w x 9.75"h] Color_R-4.2 Yellow then you'll need a 14-inch

then you'll need a 14-inch round vent

+ Product Details Size – 4"w X 12"h is the size for the duct opening measurement only

75" width X 27

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22"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 23.75"w x 9.75"h] Color_R-4.2 Yellow then you'll need a 14-inch+ Product Details Size 22"w X 8"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 23. 75" Width X 9. 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 wear