20"w X 14"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 15.75"h] Compatible With Duct 8in + Product Details Size –

+ Product Details Size – 18"w X 8"h is the size for the duct opening measurement only

+ Product Details Size – 20"w X 8"h is the size for the duct opening measurement only

75"H – fits a 18" X 4" duct opening

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+ Product Details Size - The listed 5" diameter refers specifically to the size of the duct opening

20"w X 14"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 15.75"h] Compatible With Duct 8in + Product Details Size –+ Product Details Size 20"w X 14"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 15. 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