28"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 29.75"w x 37.75"h] 14" Diameter + Product Details Size –

+ Product Details Size – 20" x 22" or 22" x 20" is the size for the duct opening measurement only

+ Product Details Size - 34"w X 30"h is the size for the duct opening measurement only

you can watch this informative video tutorial: How to Measure Your Vent Hole Before Ordering a Grille

Actual Filter Size – 7 3/4"w x 35 3/4" x 1"

28"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 29.75"w x 37.75"h] 14" Diameter + Product Details Size –+ Product Details Size 28"w X 36"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 29. 75" Width X 37. 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