36" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum Bar + Product Details Size -

+ Product Details Size - 30"w X 14"h is the size for the duct opening measurement only

+ Product Details Size – 18" x 30" or 30" x 18" is the size for the duct opening measurement only

+ Product Details Size – 8"w X 16"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 10" x 12" or 12" x 10" duct opening (measured at the opening)

36" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum Bar + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 28" OR 28" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 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