10"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 11.75"w x 21.75"h] 18in diameter Actual Filter Size – 27

Actual Filter Size – 27 3/4"w x 7 3/4" x 1"

+ Product Details Size - 12"w X 34"h X 2"d (for duct opening measurement only)

Actual Filter Size – 25 3/4"w x 23 3/4" x 1"

If your duct opening is 14 inches in diameter

10"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 11.75"w x 21.75"h] 18in diameter Actual Filter Size – 27+ Product Details Size 10"w X 20"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 11. 75" Width X 21. 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