Air-O-Swiss 7017 Ionic Silver Stick (24776) Uses the anti-microbial effect of silver to prevent the growth of microbes in the water base Begins to function as soon as it comes into contact with water, even if the unit is switched off Ensures a controlled release of silver ions, allowing for anti-microbial function in the humidifier base for the lifetime of the Ionic Silver Stick Can be used with all AIR-O-SWISS humidifiers as well as other humidifier brands as long as it does not interfere with any mechanical parts Does not need to be cleaned but should be exchanged after one year to guarantee optimal microbial protection