6" x 14" or 14" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 16.5"] Material_Aluminum + Product Details Size –

+ Product Details Size – 40"w X 10"h is the size for the duct opening measurement only

Heavier gauge than needed

+ Product Details Size – 20" x 36" or 36" x 20" is the size for the duct opening measurement only

+ Product Details Size – 28"w X 12"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 36 5/8" width X 24 5/8" height

6" x 14" or 14" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 16.5"] Material_Aluminum + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 6" x 14" or 14" x 6" duct opening (measured at the opening), with actual outer dimensions of 8. 5" W x 16. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 5. 75" x 13. 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 Made