18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 19.75"w x 19.75"h] 12" Diameter actual front end outer dimensions

actual front end outer dimensions are approximately 36 5/8" width X 14 5/8" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 34" x 30" Or 30" x 34" duct opening (measured at the opening)

+ Product Details Size - 16"w X 34"h X 2"d (for duct opening measurement only)

4" X 12" Is The Size For The Duct Opening (floor/vent hole) Measurement Only

+ Product Details Heavy-Duty Steel Construction - Made from 20-gauge steel for superior durability and reliable performance

18"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 19.75"w x 19.75"h] 12" Diameter actual front end outer dimensions+ 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