18" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Floor Grille + Product Details Size -

+ Product Details Size - 22"w X 10"h is the size for the duct opening measurement only

+ Product Details Size - 26"w X 16"h is the size for the duct opening measurement only

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+ Product Details Size - 36"w X 14"h is the size for the duct opening measurement only

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18" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Floor Grille + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 24" OR 24" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 23. 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