34" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w20h20 + Product Details Size -

+ Product Details Size - 4"w X 36"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 14 5/8" width X 38 5/8" height

Total outer size of this grille is

+ Product Details Perfect Fit & Easy Sizing - Designed for a 24" x 18" OR 18" x 24" duct opening (measured at the opening)

actual front end outer dimensions are approximately 38 5/8" width X 20 5/8" height -

34" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w20h20 + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 34" x 8" Or 8" x 34" duct opening (measured at the opening), with actual outer dimensions of 36. 5" W x 10. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 33. 75" x 7. 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