20"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 37.75"h] Width_20in Actual Filter Size – 13

Actual Filter Size – 13 3/4"w x 11 3/4" x 1"

+ Product Details Size - 28"w X 4"h is the size for the duct opening measurement only

Tailored for Your Needs: Specifically suited for 24x24 lay-in diffusers

875" width X 12" height

20"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 37.75"h] Width_20in Actual Filter Size – 13+ Product Details Size 20"w X 36"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 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