10" x 28" or 28" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 30.5"] 12" Round Duct Pipe + Product Details Size -

+ Product Details Size - 30"w X 26"h is the size for the duct opening measurement only

Actual Filter Size – 24 3/4"w x 9 3/4" x 1"

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Actual Filter Size – 33 3/4"w x 15 3/4" x 1"

+ Product Details Size - 26"w X 22"h is the size for the duct opening measurement only

10" x 28" or 28" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 30.5"] 12" Round Duct Pipe + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 28" or 28" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 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