28"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 29.75"w x 13.75"h] 18" Diameter + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 8" x 12" or 12" x 8" duct opening (measured at the opening)

+ Product Details Size – 20"w X 32"h is the size for the duct opening measurement only

The total outer size of this grille is the listed size plus plus 2 and 5/8"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 36" x 8" OR 8" x 36" duct opening (measured at the opening)

Actual Filter Size – 7 3/4"w x 35 3/4" x 1"

28"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 29.75"w x 13.75"h] 18" Diameter + Product Details Perfect Fit+ Product Details Size 28"w X 12"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 29. 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