8" x 36" or 36" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 38.5"] w24h24 + Product Details Size –

+ Product Details Size – 30"w X 14"h is the size for the duct opening measurement only

order a 14x20

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 6" or 6" x 12" duct opening (measured at the opening)

+ Product Details Size – 4"w X 14"h is the size for the duct opening measurement only

14" Diameter Is The Size For The Duct Opening Measurement Only

8" x 36" or 36" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 38.5"] w24h24 + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 36" or 36" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 75" x 35. 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