14"w X 6"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 15.75"w x 7.75"h] w34h34 + Product Details Size -

+ Product Details Size - 4"w X 18"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 16 5/8" width X 27 5/8" height

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+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 36" OR 36" x 26" duct opening (measured at the opening)

14"w X 6"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 15.75"w x 7.75"h] w34h34 + Product Details Size -+ Product Details Size 14"w X 6"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 15. 75" Width X 7. 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