8"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Black [Outer Dimensions 9.75"w x 9.75"h] 8in diameter 75"H – fits a 20"

75"H – fits a 20" X 4" duct opening

For 14" Round Duct Opening - Spiral or Flex

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actual front end outer dimensions are approximately 19

8"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Black [Outer Dimensions 9.75"w x 9.75"h] 8in diameter 75"H – fits a 20"+ Product Details Size 8"w X 8"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 9. 75" Width X 9. 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