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] 18in diameter + Product Details Size -

+ Product Details Size - 34"w X 34"h is the size for the duct opening measurement only

Designed to seamlessly integrate with T-Bar vent covers in drop ceiling setups

+ Product Details Size - 30"w X 24"h is the size for the duct opening measurement only

+ Product Details Size - 18"w X 8"h is the size for the duct opening measurement only

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] 18in diameter + 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