12"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 13.75"w x 13.75"h] 18in diameter Complies with industry standards of

Complies with industry standards of USA: ASTM D-882

For added versatility

+ Product Details Perfect Fit & Easy Sizing - Designed for a 24" x 16" OR 16" x 24" duct opening (measured at the opening)

The total outer size of this grille is the listed size plus 2

+ Product Details Size – 8" x 16" or 16" x 8" is the size for the duct opening measurement only

12"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 13.75"w x 13.75"h] 18in diameter Complies with industry standards of+ Product Details Size 12"w X 12"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 13. 75" Width X 13. 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