We upgraded our under-sink RO system and are selling our last one which is in GREAT shape and well-cared for. It is a 3-stage and still one of the top models and makes for a RO system for purified drinking water. It tests at 3 PPM for the pure water output it filters! We just replaced the filters and membrane last week before we decided to upgrade. It also includes a new sediment filter and carbon filter. It is made by REO pure. It has been running faithfully for us for a while and is in great shape!