Model PC-1. The humidifier stays cleaner, longer. Simply drop in tank for the fog fresh, clean, works in all humidifiers, maintaining cleanliness for 3 days, safe and non toxic. Antimicrobial concentrate cartridge. Continuous protection against slimy buildup in humidifier. The cleaning cartridge has patented antimicrobial Aquastat Protec continuously inhibit the growth of odor-causing bacteria and mold in the cartridge, and help prevent the accumulation of silt in the humidifier. Furthermore, the cartridge Protec offers peace of mind that the mist is fresh and clean. Safe, non-toxic Protec Cartridge uses the same antimicrobial that has been used for years in food and drinking water to prevent growth of odor-causing bacteria. The Protec cleaning cartridge is antimicrobially treated to help prevent the growth and migration of mold, mildew, algae and odor-causing bacteria in the cartridge.