10" x 6" or 6" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 8.5"] 12" Diameter + Product Details Size -

+ Product Details Size - 26"w X 36"h is the size for the duct opening measurement only

Design – Circular return valves - designed to be used in low and medium pressure ventilation air conditioning systems

+ Product Details Perfect Fit & Easy Sizing - Designed for a 14" x 24" OR 24" X 14" duct opening (measured at the opening)

+ Product Details Size – 26"w X 16"h is the size for the duct opening measurement only

10" x 6" or 6" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 8.5"] 12" Diameter + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 6" or 6" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 8. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 75" x 5. 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