36"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 37.75"w x 21.75"h] 12" Diameter + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 28" OR 28" x 18" duct opening (measured at the opening)

actual front end outer dimensions are approximately 42 5/8" width X 22 5/8" height -

Carefully Shrink Wrapped With Cardboard Backing To Prevent Damage In Shipment

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 18" or 18" x 12" duct opening (measured at the opening)

+ Product Details Size – 18" x 20" or 20" x 18" is the size for the duct opening measurement only

36"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 37.75"w x 21.75"h] 12" Diameter + Product Details Perfect Fit+ Product Details Size 36"w X 20"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 37. 75" Width X 21. 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