20"w X 22"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 23.75"h] Fixed Blades + Product Details Size -

+ Product Details Size - 28"w X 18"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 12" X 10" duct openings

180 Degrees Double Direction Adjustable - Fins Are Manually Adjustable Individually for Optimal Air Distribution

Complies with industry standards of USA: ASTM D-882

+ Product Details Size – 8" x 24" or 24" x 8" is the size for the duct opening measurement only

20"w X 22"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 23.75"h] Fixed Blades + Product Details Size -+ Product Details Size 20"w X 22"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 23. 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