18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Insulated Line + Product Details Size –

+ Product Details Size – 28"w X 12"h is the size for the duct opening measurement only

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+ Product Details Size – 18" x 20" or 20" x 18" is the size for the duct opening measurement only

Its elegant look and fine finish and the natural warmth of oak wood

+ Product Details Size - 28"w X 20"h is the size for the duct opening measurement only

18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Insulated Line + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 28" OR 28" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 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