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

+ Product Details Size - 18"w X 10"h is the size for the duct opening measurement only

equipped with a lever for airflow dampening

actual front end outer dimensions are approximately 30 5/8" width X 20 5/8" height

+ Product Details Size – 12"w X 28"h is the size for the duct opening measurement only

+ Product Details Size – 12"w X 30"h is the size for the duct opening measurement only

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