WEB Products Plus 12x12x1 Permanent Electrostatic Air Filter Permanent Electrostatic Filter is certified to remove up to 91&#37; of dust particles from your air. This washable&#47;reusable filter replaces standard ac&#47;furnace filters. WEB Three Phase Electrostatic Filter Traps up to 91&#37; of pollen&#44; dust and dander sized particles from 0.245 to 80 microns Simple rinse and reuse