6" x 28" or 28" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 30.5"] RG66 Black-HP + Product Details Size –

+ Product Details Size – 20" x 30" or 30" x 20" is the size for the duct opening measurement only

Actual Filter Size – 11 3/4"w x 13 3/4" x 1"

Actual Filter Size – 7 3/4"w x 29 3/4" x 1"

6" x 6" - opening (vent hole - Neck Size) dimension - actual size is approx 2" wider

Adjust the airflow to your preference by simply opening or closing the top panel

6" x 28" or 28" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 30.5"] RG66 Black-HP + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 6" x 30" or 30" x 6" duct opening (measured at the opening), with actual outer dimensions of 8. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 5. 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 Made