26" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Round Damper Ring + Product Details Size -

+ Product Details Size - 24"w X 30"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

+ Product Details Size – 14"w X 25"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 20" or 20" x 12" duct opening (measured at the opening)

+ Product Details Size – 18"w X 26"h is the size for the duct opening measurement only

26" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Round Damper Ring + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 26" x 28" OR 28" x 26" duct opening (measured at the opening), with actual outer dimensions of 28. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 25. 75" x 27. 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