New for 2014! The Hydro Cell replaces the Hydro Stick or Silver Stick and is compatible in all humidifiers that use the Hydro Stick or Silver Stick. The new Hydro Cell is placed into the water tank instead of inside the base of the humidifier. The AIROSWISS Hydro Cell AOS A200 (replaces Hydro Stick and Ionic Silver Stick) is an advanced water maintenance system with activated carbon technology to provide constant freshness in AIR-O-SWISS Humidifiers and Air Washers. The Hydro Cell is simply placed inside the water tank, and begins working as soon as it comes into contact with water, even if the humidifier is turned off. Fits Models AIR-O-SWISS: 7131 (AOS 7131), 7133 (AOS 7133), 7135 (AOS 7135), 7142 (AOS U7142), 7144 (AOS 7144), 7145 (AOS 7145), 7147 (AOS 7147), U200 (AOS U200), U600 (AOS U600), U650 (AOS U650), U700 ( AOS U700), E2441 (AOS E2441), 1355 (AOS 1355N), 2055 (AOS 2055), 2055A (AOS 2055A), 2055D (AOS 2055D). Featuring Activated Carbon Technology: Activated carbon is a highly adsorptive form of carbon treated with oxygen used to remove impurities from liquids. Also used to filter drinking water, activated carbon reduces heavy metals (such as lead, copper and mercury), organic impurities and pesticides that may be present in your household tap water. Protected with Ag+ Technology, activated carbon reduces the growth of odor causing chemicals and biofilm to keep your humidifier fresh and clean. Placement of Hydro Cell: Rinse Hydro Cell for 30 seconds prior to first use. Place one Hydro Cell into your water tank prior to filling. Contains 2 (two) Hydro Cells Replace every 1 to 2 months, depending on your water quality.