8" x 30" or 30" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 32.5"] 6" Round Duct Pipe + Product Details Size -

+ Product Details Size - 12"w X 8"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 10 5/8" width X 26 5/8" height

Actual Filter Size – 15 3/4"w x 15 3/4" x 1"

+ Product Details Size – 8" x 36" or 36" x 8" is the size for the duct opening measurement only

8" x 30" or 30" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 32.5"] 6" Round Duct Pipe + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 30" or 30" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 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