10" x 28" or 28" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 30.5"] 12" Round Duct Pipe /* Adding space between bullet

/* Adding space between bullet points */ } li { margin-bottom: 15px

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 25" OR 25" x 20" duct opening (measured at the opening)

Actual Filter Size – 33 3/4"w x 15 3/4" x 1"

+ Product Details Size – 20"w X 50"h is the size for the duct opening measurement only

10" x 28" or 28" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 30.5"] 12" Round Duct Pipe /* Adding space between bullet+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 28" or 28" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 75" x 27. 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