20"w X 6"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 7.75"h] 14in diameter + Product Details Size –

+ Product Details Size – 30"w X 24"h is the size for the duct opening measurement only

+ Product Details Size - 18"w X 26"h X 2"d (for duct opening measurement only)

Design – removable frame for easy filter change & cleaning - uses a 1" thick filter

+ Product Details Size - 14"w X 22"h X 2"d (for duct opening measurement only)

actual front end outer dimensions are approximately 16 5/8" width X 18 5/8" height

20"w X 6"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 7.75"h] 14in diameter + Product Details Size –+ Product Details Size 20"w X 6"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 7. 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 wear