24" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 12" X 8" duct openings

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

+ Product Details Size - 10"w X 6"h is the size for the duct opening measurement only

Actual Filter Size – 11 3/4"w x 7 3/4" x 1"

24" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter Ideal for Walls & Ceilings:+ Product Details Perfect Fit & Easy Sizing Designed for a 24" x 28" OR 28" x 24" duct opening (measured at the opening), with actual outer dimensions of 26. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 23. 75" x 27. 75" x 1" Premium Airflow Efficiency High performance cube core eggcrate design allows 95% airflow efficiency, reducing energy costs and maximizing HVAC system lifespan. Durable, Rust Free Aluminum