6" x 36" or 36" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 38.5"] 12in diameter + Product Details Size -

+ Product Details Size - 34"w X 34"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 12" duct openings

+ Product Details Size – 18"w X 12"h is the size for the duct opening measurement only

The lightweight yet rigid construction ensures durability without sacrificing ease of handling

6" x 36" or 36" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 38.5"] 12in diameter + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 6" x 36" or 36" x 6" duct opening (measured at the opening), with actual outer dimensions of 8. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 5. 75" x 35. 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