Disinfecting Filtration System Technology , referred to as EMF high-efficiency filtration system, is a unique air purification technology of HealthWay . Inspired by the military air sterilization technology for purifying the closed environment inside nuclear submarines , HealthWay has evolved into today's DFS technology after 30 years of development. It has obtained patents in more than 40 countries around the world, and more than 20 utility model and invention patents in China alone. HealthWay air sterilizers equipped with this technology have passed the inspection of the US Food and Drug Administration (FDA) and are certified as Class II medical devices.