20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 24" x 36" OR 36" x 24" duct opening (measured at the opening)

+ Product Details Size - 10"w X 14"h is the size for the duct opening measurement only

Horizontal performance assures confident use of cooling temperature differential of 30 degrees Fahrenheit and greater

This thoughtful design ensures optimal air circulation for your HVAC system

20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar + Product Details Perfect Fit+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 18" OR 18" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 75" x 17. 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