16"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 17.75"w x 9.75"h] 1-Way + Product Details Size -

+ Product Details Size - 16"w X 30"h is the size for the duct opening measurement only

+ Product Details Size - 25"w X 24"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 4" duct openings

actual front end outer dimensions are approximately 22 5/8" width X 42 5/8" height -

16"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 17.75"w x 9.75"h] 1-Way + Product Details Size -+ Product Details Size 16"w X 8"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 17. 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