20" x 30" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w30h30 + Product Details Size -

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

With a 8" diameter for the duct opening measurement

providing efficient performance of up to 300m3/h

+ Product Details Size - The listed 8" diameter refers specifically to the size of the duct opening

20" x 30" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w30h30 + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 30" OR 30" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 75" x 29. 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