26" x 6" or 6" x 26" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 10" Round Duct Pipe + Product Details Size -

+ Product Details Size - 30"w X 4"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 12" X 8" duct openings

+ Product Details Size - 36"w X 10"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 16 5/8" width X 14 5/8" height

26" x 6" or 6" x 26" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 10" Round Duct Pipe + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 26" x 6" OR 6" x 26" duct opening (measured at the opening), with actual outer dimensions of 28. 5" W x 8. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 25. 75" x 5. 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