18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Width_20in + Product Details Size -

+ Product Details Size - 30"w X 32"h is the size for the duct opening measurement only

75"H – fits a 18" X 12" duct opening

Just run your finger along the edge of the top plate and you’ll find a smooth finished surface

actual front end outer dimensions are 37

18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Width_20in + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 28" OR 28" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 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