28" x 34" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible with Duct 6" + Product Details Size -

+ Product Details Size - 40"w X 20"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 6" OR 6" x 20" duct opening (measured at the opening)

Adjustable airflow control - by rotating the middle disk

The grille comes with all necessary screws for a secure fit

+ Product Details Size – 26"w X 16"h is the size for the duct opening measurement only

28" x 34" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible with Duct 6" + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 28" x 34" OR 34" x 28" duct opening (measured at the opening), with actual outer dimensions of 30. 5" W x 36. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 27. 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