Model PC-1 replacement filter. Keeps your humidifier cleaner, longer. Simply drop in tank for fresh, clean mist; keeps cleaning for 30 days. Kills bacteria that can cause unpleasant odors. Continuously cleans and protects humidifiers against bacteria & mold. Contains: 1 filter. As gentle as water cleaning action (Aquastat imparts no harsh oxidizers or bleach compounds making the cleaning action as gentle as water on your humidifier. In addition the Protec Cartridge provides peace of mind that the mist is fresh and clean). The Protec Antimicrobial Cleaning Cartridge features a patented antimicrobial, Aquastat, that continuously works to inhibit the growth of bacteria and mold as well as help prevent the buildup of slime in the water and humidifier surfaces. The Protec Antimicrobial Cleaning Cartridge uses the same antimicrobial that has been used for years to control odor-causing bacteria and unsightly mold in drinking water filters. Made in USA.