36" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter actual front end outer dimensions

actual front end outer dimensions are approximately 36 5/8" width X 12 5/8" height

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actual front end outer dimensions are approximately 18 5/8" width X 12 5/8" height -

+ Product Details Size – 26"w X 18"h is the size for the duct opening measurement only

Actual Filter Size – 31 3/4"w x 27 3/4" x 1"

36" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 12" OR 12" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 14. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 75" x 11. 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