18" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter actual front end outer dimensions

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

+ Product Details Size – 18"w X 20"h is the size for the duct opening measurement only

Installation Location – Sidewall & ceiling

reducing energy costs and maximizing HVAC system lifespan

5" - SEE BELOW IN DESCRIPTION HOW TO MEASURE A GRILLE

18" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 24" OR 24" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 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