20"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 13.75"h] 6in diameter + Product Details Size –

+ Product Details Size – 20"w X 4"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 22 5/8" width X 12 5/8" height -

actual front end outer dimensions are approximately 14 5/8" width X 34 5/8" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 30" x 12" OR 12" x 30" duct opening (measured at the opening)

actual front end outer dimensions are approximately 41

20"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 13.75"h] 6in diameter + Product Details Size –+ Product Details Size 20"w X 12"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 13. 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