28" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 8" x 6" or 6" x 8" duct opening (measured at the opening)

Easy clean Healthy air flow for your HVAC system - noise free components - no vibrating louvers etc

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 24" OR 24" X 16" duct opening (measured at the opening)

Marked circles for cutout

28" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8in diameter + Product Details Perfect Fit+ Product Details Perfect Fit & Easy Sizing Designed for a 28" x 18" OR 18" x 28" duct opening (measured at the opening), with actual outer dimensions of 30. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 27. 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