26" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w28h28 + Product Details 12"w X

+ Product Details 12"w X 4"h Is The Size For The Duct Opening Measurement Only

+ Product Details Size – 6" x 6" is the size for the duct opening measurement only

Design – Equipped with lever for full airflow control

For 12" Round Duct Opening - Spiral or Flex

26" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w28h28 + Product Details 12"w X+ Product Details Perfect Fit & Easy Sizing Designed for a 26" x 18" OR 18" x 26" duct opening (measured at the opening), with actual outer dimensions of 28. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 25. 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