HVAC Premium 18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 19.75"h] w8h8 + Product Details Size –

+ Product Details Size – 14" X 4" is the size for the duct opening (floor/vent hole) measurement only

4" X 12" Is The Size For The Duct Opening (floor/vent hole) Measurement Only

+ Product Details Size - 12"w X 36"h is the size for the duct opening measurement only

+ Product Details Size – 8"w X 26"h is the size for the duct opening measurement only

HVAC Premium 18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 19.75"h] w8h8 + 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