10" x 18" or 18" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 20.5"] 18" Round Duct Pipe + Product Details Size –

+ Product Details Size – 14"w X 18"h is the size for the duct opening measurement only

Actual Filter Size – 25 3/4"w x 27 3/4" x 1"

Engineered with precision and designed to perfection

actual front end outer dimensions are approximately 22 5/8" width X 20 5/8" height -

The total outer size of this grille is the listed size plus 3"

10" x 18" or 18" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 20.5"] 18" Round Duct Pipe + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 18" or 18" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 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