20"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 21.75"w x 21.75"h] Grilles + Product Details Perfect Fit

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

+ Product Details Size - 8"w X 24"h is the size for the duct opening measurement only

+ Product Details Size - 22"w X 16"h is the size for the duct opening measurement only

By simply measuring the width or the length of the vent

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 36" OR 36" X 16" duct opening (measured at the opening)

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