8" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 10.5"] 18in diameter + Product Details Size –

+ Product Details Size – 8"w X 16"h is the size for the duct opening measurement only

listed size +2"

The ring base allows installation without removing the thermostat

+ Product Details Size – 8"w X 14"h is the size for the duct opening measurement only

The total outer size of this grille is the listed size plus 2 and 5/8"

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