14"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 15.75"w x 9.75"h] 18" Round Duct Pipe then you'll need a 14-inch

then you'll need a 14-inch round vent

it ensures long-lasting durability

Actual Filter Size – 13 3/4"w x 5 3/4" x 1"

Heavy Gauge Steel – Heavier gauge than needed

actual front end outer dimensions are approximately 32 5/8" width X 28 5/8" height

14"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 15.75"w x 9.75"h] 18" Round Duct Pipe then you'll need a 14-inch+ Product Details Size 14"w X 8"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 15. 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