18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 19.75"w x 19.75"h] Width_20in + Product Details Size –

+ Product Details Size – 18" x 24" or 24" x 18" is the size for the duct opening measurement only

Actual Filter Size – 31 3/4"w x 27 3/4" x 1"

+ Product Details Size – 16" x 24" or 24" x 16" is the size for the duct opening measurement only

+ Product Details Size – 8"w X 14"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 16 5/8" width X 18 5/8" height

18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 19.75"w x 19.75"h] Width_20in + Product Details Size –+ Product Details Size 18"w X 18"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 19. 75" Width X 19. 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