8"w X 30"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 31.75"h] fixed bar + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size – 36"w X 20"h is the size for the duct opening measurement only

+ Product Details Outer dimensions: 19

actual front end outer dimensions are approximately 20 5/8" width X 8 5/8" height

+ Product Details Size - 24"w X 20"h X 2"d (for duct opening measurement only)

+ Product Details Size – 18"w X 30"h is the size for the duct opening measurement only

8"w X 30"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 9.75"w x 31.75"h] fixed bar + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 36"w X 20"h is the size for the duct opening measurement only + Product Details Outer dimensions: 19