8"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 9.75"w x 17.75"h] w34h34 + Product Details Size -

+ Product Details Size - The listed 10" diameter refers specifically to the size of the duct opening

+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 30" OR 30" x 26" duct opening (measured at the opening)

actual front end outer dimensions are approximately 10 5/8" width X 22 5/8" height

the gap will expand and retract to meet perfect air supply needed

8"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 9.75"w x 17.75"h] w34h34 + Product Details Size -+ 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