Permatron Corp. (Franklin Park, IL) says its electrostatic air filters are designed to help improve the indoor air quality in a number of commercial-industrial environments. Model IN is designed for commercial applications where low resistance and cleanability are critical, such as schools and offices. The DuraLoft(r), for industrial applications, is designed to withstand high-velocity airflow, heavy dirt loads, and rigorous maintenance programs. And Model HFA is designed for high-efficiency particulate removal, as needed in hospitals, labs, and electronic and computer assembly areas.