20" x 36" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grilles + Product Details Size -

+ Product Details Size - 30"w X 36"h is the size for the duct opening measurement only

+ Product Details Size – 25"w X 36"h is the size for the duct opening measurement only

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actual front end outer dimensions are approximately 18 5/8" width X 36 5/8" height

20" x 36" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grilles + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 36" OR 36" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 75" x 35. 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