10" x 34" or 34" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 36.5"] Filter Grille Actual Filter Size – 21

Actual Filter Size – 21 3/4"w x 11 3/4" x 1"

optimizing performance and energy efficiency

Actual Filter Size – 33 3/4"w x 13 3/4" x 1"

+ Product Details Size - 36"w X 10"h is the size for the duct opening measurement only

10" x 34" or 34" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 36.5"] Filter Grille Actual Filter Size – 21+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 34" or 34" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 36. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 75" x 33. 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