8"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 9.75"w x 9.75"h] Width_20in Filter Size - 33

Filter Size - 33

Actual Filter Size – 9 3/4"w x 17 3/4" x 1"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 36" x 20" OR 20" x 36" duct opening (measured at the opening)

+ Product Details Perfect Fit & Easy Sizing - Designed for a 34" x 24" Or 24" x 34" duct opening (measured at the opening)

+ Product Details Size – 6" x 8" or 8" x 6" is the size for the duct opening measurement only

8"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Brown [Outer Dimensions 9.75"w x 9.75"h] Width_20in Filter Size - 33+ Product Details Size 8"w X 8"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 9. 75" Width X 9. 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 wear