Features: 1. In order to get clean water and fresh air, at least every 1-2 month or every 30 - 40 fillings replaces cartridge would be better, which will vary based on water hardness and frequency of using. 2. Just put a new Cartridge into the tank and it works. You will begin enjoying clean, pure mist. please carefully verify whether your humidifiers can load it into. 3. This Premium Demineralization Filters can help extend the life of your humidifier motor and tank by purifying the water inside and keeping it clean. 4. The ultrasonic filter helps to prevent the build-up of white dust caused by minerals and chemical in hard water. 5. These Demineralization Filters can help extend the life of your humidifier motor and tank by purifying the water inside and keeping it clean. Humidifier Replacement Cartridges Ultrasonic Demineralization Humidifier Replacement Cartridges Filters Mineral Deposits For HoMedics Preventing Odor In order to get clean water and fresh air, at least every 1-2 month or every 30 - 40 fillings replaces cartridge would be better, which will vary based on water hardness and frequency of using.