10" x 36" or 36" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 38.5"] Compatible with Duct 6" actual front end outer dimensions

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

Universal Fit – Measures 3-7/8" wide x 3-1/2" high x 3" deep

+ Product Details Size – 10"w X 16"h is the size for the duct opening measurement only

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

Total outer size of this grille is

10" x 36" or 36" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 38.5"] Compatible with Duct 6" actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 36" or 36" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 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