20"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 25.75"h] Ceiling Actual Filter Size – 35 4 X 12 Is CRFG2028 Width_14in

Actual Filter Size – 35 3/4"w x 33 3/4" x 1"

Adjustable airflow control - by rotating the middle disk

+ Product Details Perfect Fit & Easy Sizing - Designed for a 32" x 36" Or 36" x 32" duct opening (measured at the opening)

ensuring it arrives at your home in perfect condition

+ Product Details Size - 16"w X 12"h is the size for the duct opening measurement only

20"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 21.75"w x 25.75"h] Ceiling Actual Filter Size – 35 4 X 12 Is CRFG2028 Width_14in Actual Filter Size – 35 3 4"w x 33 3 4" x 1" Adjustable airflow control by rotating the middle disk