8" x 18" or 18" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 20.5"] Supply Grille + Product Details Size –

+ Product Details Size – 16"w X 18"h is the size for the duct opening measurement only

6" width X 13

height: 20px

1/4" - 6518 PSI

Scratch-Resistant Finish - The powder-coated surface offers a smooth

8" x 18" or 18" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 20.5"] Supply Grille + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 18" or 18" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 75" x 17. 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