This HEPA particle filter replacement is designed for Blueair Classic 400 Series air purifiers, including models 402, 403, 405, 410, 450E, 455EB, and 480i. The filter measures 20.47 inches by 9.84 inches by 3.74 inches and features high-efficiency particulate air construction that captures fine particles and common irritants from the air. The professional-grade design maintains proper airflow while filtering pollutants, helping your air purifier operate effectively. This is a third-party replacement filter, not an original equipment manufacturer part, but it is engineered to fit Blueair 400 se