6"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 7.75"w x 17.75"h] Compatible With Duct 10in + Product Details Size –

+ Product Details Size – 20"w X 18"h is the size for the duct opening measurement only

Actual Filter Size – 9 3/4"w x 11 3/4" x 1"

Actual Filter Size – 17 3/4"w x 17 3/4" x 1"

With plain ends

actual front end outer dimensions are approximately 38 5/8" width X 26 5/8" height -

6"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 7.75"w x 17.75"h] Compatible With Duct 10in + Product Details Size –+ Product Details Size 6"w X 16"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 7. 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