A large amount of ions generated from pure supply is, harmful substances (allergens such as various virus pollen, PM2.5 etc) floating around your face removal. PM2.5 (2.5μm or less), pollen allergens (1μm or less), ultra-fine particulate matter 0.02μm also removed. Third-party testing organization proven. (It is not the result of real use space) Complete silence, no wind, odorless. Running in a complete silence. Harsh sound, wind, no smell. Only 50g. Lightweight enough to become even forget that you are wearing. About two weeks running at once of charge (in the case of 10 hours per day use) (up to 150 hours duration charging battery)