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 The total outer size of

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

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ISO Supply Diffusers perform efficiently with air loadings of 6 to 30 air changes per hour (based on 10 ft

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

Engineered with precision and designed to perfection

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 The total outer size of+ 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