28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Material_Aluminum + Product Details Size –

+ Product Details Size – 36"w X 26"h is the size for the duct opening measurement only

+ 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 36 5/8" width X 14 5/8" height

+ Product Details Size – 22"w X 25"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 34 5/8" width X 12 5/8" height -

28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Material_Aluminum + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 28" x 24" OR 24" x 28" duct opening (measured at the opening), with actual outer dimensions of 30. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 27. 75" x 23. 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