6" x 34" or 34" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 36.5"] Compatible With Duct 8in + Product Details Size -

+ Product Details Size - 22"w X 10"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 22" x 36" OR 36" x 22" duct opening (measured at the opening)

actual front end outer dimensions are approximately 22 5/8" width X 14 5/8" height -

+ Product Details Size - 28"w X 28"h is the size for the duct opening measurement only

you can watch this informative video tutorial: How to Measure Your Vent Hole Before Ordering a Grille

6" x 34" or 34" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 36.5"] Compatible With Duct 8in + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 6" x 34" or 34" x 6" duct opening (measured at the opening), with actual outer dimensions of 8. 5" W x 36. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 5. 75" x 33. 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 Made