The NEX is a multi-unit modular system. There are 2 choices with the NEX: The water processing unit and the water storage tank. The unit is meant to be customizable for your current needs and any future expansion. Since the units are separate they can fit into smaller places. They do not need to be placed right next to each other. Optional water processor rack if there is no mounting location. The NEX reinvents the standard for reformulating water.