20"w X 28"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 29.75"h] 14in diameter + Product Details Size –

+ Product Details Size – 16" x 36" or 36" x 16" is the size for the duct opening measurement only

+ Product Details Size - 8"w X 30"h is the size for the duct opening measurement only

Performance – High diffusion induction rates result in rapid temperature and velocity equalization of the mixed air mass well above the zone of occupancy

+ Product Details Size - 36"w X 10"h is the size for the duct opening measurement only

then you'll need a 14-inch round vent

20"w X 28"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 29.75"h] 14in diameter + Product Details Size –+ Product Details Size 20"w X 28"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 29. 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