8" x 16" or 16" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 18.5"] Black + Product Details Size -

+ Product Details Size - 16"w X 28"h is the size for the duct opening measurement only

this flex duct decreases the pressure loss and provides a more hygienic environment

actual front end outer dimensions are approximately 18 5/8" width X 28 5/8" height

+ Product Details Size - 20"w X 30"h is the size for the duct opening measurement only

8" x 16" or 16" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 18.5"] Black + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 16" or 16" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 18. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 75" x 15. 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