8" x 14" or 14" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 16.5"] 6in diameter + Product Details Size –

+ Product Details Size – 24"w X 20"h is the size for the duct opening measurement only

+ Product Details Size - 14"w X 36"h is the size for the duct opening measurement only

For 14" duct opening

actual front end outer dimensions are approximately 12 5/8" width X 26 5/8" height

+ Product Details Size – 14" x 36" or 36" x 14" is the size for the duct opening measurement only

8" x 14" or 14" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 16.5"] 6in diameter + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 14" or 14" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 16. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 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