16"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 17.75"w x 19.75"h] 18in diameter Actual Filter Size – 15

Actual Filter Size – 15 3/4"w x 31 3/4" x 1"

+ Product Details Size - 8"w X 30"h is the size for the duct opening measurement only

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Filter Size - 27

+ Product Details Size - 10"w X 22"h is the size for the duct opening measurement only

16"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 17.75"w x 19.75"h] 18in diameter Actual Filter Size – 15+ Product Details Size 16"w X 18"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 17. 75" Width X 19. 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