Establish an enjoyable breathing experience for you and those around you with this demineralization cartridge. Cartridge attaches to the inside of your tank to force water to pass through for increased efficiency. Advanced system helps neutralize minerals and reduce calcium in hard water, which can cause white dust, before it's distributed into the air. For optimal performance, replace the cartridge every 20 to 30 fillings for the very best results. Cartridge is designed for use with the Honeywell ultrasonic humidifier (sold separately).