34"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 35.75"w x 37.75"h] 14" Diameter actual front end outer dimensions

actual front end outer dimensions are approximately 34 5/8" width X 16 5/8" height

actual front end outer dimensions are approximately 16 5/8" width X 8 5/8" height

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

actual front end outer dimensions are approximately 24 5/8" width X 22 5/8" height

and the second number represents the height

34"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 35.75"w x 37.75"h] 14" Diameter actual front end outer dimensions+ Product Details Size 34"w X 36"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 35. 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