10" x 30" or 30" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 32.5"] Compatible With Duct 10in + Product Details Size -

+ Product Details Size - 4"w X 34"h is the size for the duct opening measurement only

+ Product Details Size - 24"w X 32"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 34 5/8" width X 18 5/8" height

+ Product Details Size - 34"w X 4"h is the size for the duct opening measurement only

10" x 30" or 30" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 32.5"] Compatible With Duct 10in + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 30" or 30" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 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