20"w X 32"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 33.75"h] 14" 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 - 8"w X 18"h X 2"d (for duct opening measurement only)

Actual Front End Outer Dimensions Are 14" Width X 10" Height - SEE IN DESCRIPTION HOW TO MEASURE A GRILLE

+ Product Details Size - 16"w X 24"h is the size for the duct opening measurement only

See chart below:

20"w X 32"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 33.75"h] 14" Diameter + Product Details Perfect Fit+ Product Details Size 20"w X 32"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 33. 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