18" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w25h25 actual front end outer dimensions

actual front end outer dimensions are approximately 2" wider

+ Product Details Size - 26"w X 6"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 29

Filter Size - 11

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 24" or 24" x 12" duct opening (measured at the opening)

18" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w25h25 actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 20. 75" x 20. 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 Made from