12" x 28" or 28" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter flat stamped steel + Product Details Outer dimensions:

+ Product Details Outer dimensions: 11

+ Product Details Size – 16" x 18" or 18" x 16" is the size for the duct opening measurement only

+ Product Details Size – 16"w X 20"h is the size for the duct opening measurement only

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12" x 28" or 28" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter flat stamped steel + Product Details Outer dimensions:+ Product Details Perfect Fit & Easy Sizing Designed for a 12" x 28" or 28" x 12" duct opening (measured at the opening), with actual outer dimensions of 14. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 11. 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