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"] Floor Grille + Product Details Size -

+ Product Details Size - 20"w X 22"h X 2"d (for duct opening measurement only)

But they are also the most visible representation of you air system

+ Product Details Size – 24"w X 22"h is the size for the duct opening measurement only

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

Equipped with a lever to adjust airflow to your preference

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"] Floor Grille + 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