18" x 26" or 26" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18" Diameter 875" width X 10" height

875" width X 10" height

+ Product Details Size – 16" x 18" or 18" x 16" is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 36" or 36" x 12" duct opening (measured at the opening)

actual front end outer dimensions are approximately 26 5/8" width X 16 5/8" height

18" x 26" or 26" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18" Diameter 875" width X 10" height+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 26" OR 26" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 28. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 27. 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