8"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 17.75"h] Curved Blade Steel } li { margin-bottom: 15px

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+ Product Details Size - 16"w X 20"h X 2"d (for duct opening measurement only)

+ Product Details Size – 12"w X 16"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 36" x 30" OR 30" x 36" duct opening (measured at the opening)

The first number in a grille size represents the width

8"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 9.75"w x 17.75"h] Curved Blade Steel } li { margin-bottom: 15px+ Product Details Size 8"w X 16"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 9. 75" Width X 17. 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