The Protec Antimicrobial Cleaning Cartridge features a patented antimicrobial, Aquastat that continuously works to hinder the growth of bacteria and mold. It's also capable of preventing the buildup of slime in the water and humidifier surfaces. These Protec Antimicrobial Cleaning Cartridges work in all humidifiers and are safe/non-toxic. Aquastat contains no harsh chemicals or harsh acids making the cleaning action just as gentle as water on your humidifier surfaces and components. In addition, the Protec Cartridge contains no harmful chemicals while providing fresh, clean mist. The Protec Antimicrobial Cleaning Cartridge uses the same antimicrobial that has been used for years in drinking water filters to prevent objectionable odors and tastes.