HM Digital TDS-3 Handheld TDS Meter is a valuable device for conveniently checking the Total Dissolved Solids (TDS) in your home's water supply or the output of your RO/DI unit. This unit is equipped with a digital display, a built-in thermometer, and includes a practical carrying case for easy portability. As is the standard with all HM-Digital products, the TDS-3 comes pre-calibrated from the factory, ensuring reliable and accurate measurements.