Available in two versions; the 30ppm Filter, which purifies water to 30 parts per million & delivers spot free results when hand washing vehicles. Alternatively, the 0ppm Aqua Gleam De-ioniser Filter purifies ordinary water to 0 parts per million - water at this level of purity will provide excellent spot free results Filters have colour change mechanism, utilising the resin that purifies the water. This changes colour when being used, indicating when it should be changed.