36"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 37.75"w x 25.75"h] with filter + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size – 10" x 16" or 16" x 10" is the size for the duct opening measurement only

during winter

+ Product Details Size - 20"w X 16"h is the size for the duct opening measurement only

+ Product Details Size – 10"w X 28"h is the size for the duct opening measurement only

875" width X 22" height

36"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 37.75"w x 25.75"h] with filter + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 10" x 16" or 16" x 10" is the size for the duct opening measurement only during winter