12" x 28" or 28" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Black + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 6" x 10" or 10" x 6" duct opening (measured at the opening)

and squirrels

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+ Product Details Size – 20"w X 14"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 22 5/8" width X 20 5/8" height -

12" x 28" or 28" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Black + Product Details Perfect Fit+ 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