The Protec Replacement Humidifier Filter is specially treated to reduce growth and migration of particles on the filter. It's an extended life humidifier replacement filter that fits Vicks Cool Mist Humidifier Models: V3500, V3100, V3600, V3900 & 3020. At Vicks, we believe that everyone deserves a touch of care. Our line of humidifiers, steam inhalers and vaporizer help you breathe better and sleep more comfortably, wherever you are.