10" x 26" or 26" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 28.5"] Filter Grille Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 10" X 6" duct openings

+ Product Details Size – 10"w X 10"h is the size for the duct opening measurement only

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

actual front end outer dimensions are approximately 12 5/8" width X 36 5/8" height

10" x 26" or 26" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 28.5"] Filter Grille Ideal for Walls & Ceilings:+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 26" or 26" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 28. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 75" x 25. 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