18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 19.75"w x 19.75"h] 8in diameter + Product Details Size –

+ Product Details Size – 18"w X 34"h is the size for the duct opening measurement only

Filter Size - 35

+ Product Details Size – 14"w X 10"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 10" x 36" or 36" x 10" duct opening (measured at the opening)

18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 19.75"w x 19.75"h] 8in diameter + Product Details Size –+ Product Details Size 18"w X 18"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 19. 75" Width X 19. 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