18"w X 30"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 31.75"h] 10" Diameter Actual Filter Size – 29

Actual Filter Size – 29 3/4"w x 27 3/4" x 1"

+ Product Details Size - 12"w X 20"h is the size for the duct opening measurement only

+ Product Details Size - 10"w X 22"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 18" OR 18" X 16" duct opening (measured at the opening)

18"w X 30"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 31.75"h] 10" Diameter Actual Filter Size – 29+ Product Details Size 18"w X 30"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 19. 75" Width X 31. 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