The NPET Pet Automatic Water Supply WF020 filter is more than other water supply filters, Circulation Use Technology, 4-Layer Filtration System, Activated Carbon Filter, Ion Exchange Resin, This filter removes dust, food residue, pet hair, residual chlorine, odor Magnesium and calcium contained in tap water, thoroughly filters pet drinking water and provides clean water. Circulation Use Technology: Ditch non-woven fabric that is prone to mildew and uses innovative circulation technology that allows you to use it for up to six years with a single filter. Please clean the filter at least once a week, as pet hair may collect on the filter. If the hair that collects in the filter cannot be cleaned, please replace a new filter.