6" x 16" or 16" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 18.5"] Adjustable Return + Product Details Size –

+ Product Details Size – 28"w X 26"h is the size for the duct opening measurement only

+ Product Details Size – 28"w X 24"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 22" OR 22" X 16" duct opening (measured at the opening)

+ Product Details Size – 18"w X 25"h is the size for the duct opening measurement only

6" x 16" or 16" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 18.5"] Adjustable Return + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 6" x 16" or 16" x 6" duct opening (measured at the opening), with actual outer dimensions of 8. 5" W x 18. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 5. 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 Made