8"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 19.75"h] 6" Diameter The first number in a

The first number in a grille size represents the width

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

Equipped with a lever for easy airflow adjustment and dampening

Whether you choose the modern contemporary

and slashes energy costs

8"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 19.75"h] 6" Diameter The first number in a+ Product Details Size 8"w X 18"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 9. 75" Width X 19. 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