20"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 17.75"h] Fixed Blades with Damper Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 10" X 6" duct openings

+ Product Details Perfect Fit & Easy Sizing - Designed for a 34" x 24" Or 24" x 34" duct opening (measured at the opening)

actual front end outer dimensions are 13

Installation Location – Suitable for both sidewall and ceiling installation

20"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 17.75"h] Fixed Blades with Damper Ideal for Walls & Ceilings:+ Product Details Size 20"w X 16"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 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