24"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 25.75"w x 25.75"h] 10in diameter + Product Details Size -

+ Product Details Size - 26"w X 16"h is the size for the duct opening measurement only

+ Product Spec Sheet Aluminum Return Filter Grille Spec Sheet

+ Product Details Size - 28"w X 6"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 10" x 18" or 18" x 10" duct opening (measured at the opening)

24"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 25.75"w x 25.75"h] 10in diameter + Product Details Size -+ Product Details Size 24"w X 24"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 25. 75" Width X 25. 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