10" x 24" or 24" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 26.5"] Return Grille + Product Details Size –

+ Product Details Size – 8" x 18" or 18" x 8" is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 26" or 26" x 12" duct opening (measured at the opening)

+ Product Details Size – 30" x 36" or 36" x 30" is the size for the duct opening measurement only

actual front end outer dimensions are approximately 27 5/8" width X 30 5/8" height

+ Product Details Size - 22"w X 34"h is the size for the duct opening measurement only

10" x 24" or 24" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 26.5"] Return Grille + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 24" or 24" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 75" x 23. 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