34" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w36h36 + Product Details Size -

+ Product Details Size - 16"w X 30"h is the size for the duct opening measurement only

positioning supply and return grills accordingly

12"w X 3"h Is The Size For The Duct Opening Measurement Only

8" Diameter Is The Size For The Duct Opening Measurement Only

34" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w36h36 + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 34" x 18" Or 18" x 34" duct opening (measured at the opening), with actual outer dimensions of 36. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 33. 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