8"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 9.75"w x 17.75"h] Aluminum - Cube Core + Product Details Size -

+ Product Details Size - 26"w X 20"h is the size for the duct opening measurement only

High Quality – Solid stamped steel with counter-sunk screw holes (screws included) and no sharp edges

Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 18" duct openings

actual front end outer dimensions are approximately 14 5/8" width X 22 5/8" height

8"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 9.75"w x 17.75"h] Aluminum - Cube Core + Product Details Size -+ Product Details Size 8"w X 16"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 9. 75" Width X 17. 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