8"w X 30"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 31.75"h] w10h10 + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 6" x 36" or 36" x 6" duct opening (measured at the opening)

actual front end outer dimensions are approximately 12 5/8" width X 20 5/8" height

With a 8" diameter for the duct opening measurement

+ Product Details Size - 36"w X 28"h is the size for the duct opening measurement only

the actual front end outer dimensions are 8" in diameter

8"w X 30"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 31.75"h] w10h10 + Product Details Perfect Fit+ Product Details Size 8"w X 30"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 9. 75" Width X 31. 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