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 Ideal for Walls & Ceilings: Suitable for all AC 8in diameter 12125SDCLNGBX

Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 8" duct openings

Adjustable airflow control - by rotating the middle disk

actual front end outer dimensions are approximately 16 5/8" width X 22 5/8" height

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

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 Ideal for Walls & Ceilings: Suitable for all AC 8in diameter 12125SDCLNGBX Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 8" duct openings Adjustable airflow control by rotating the middle disk