The model 512 single range DS Meter is a compact instrument that operates on the principal of electrical conductivity. It will quickly determine the conductivity or ppm/Total Dissolved Solids of almost any solution. Conductivity is then converted directly into parts per million (ppm) of Total Dissolved Solids. All are 3.4" x 4.5" x 4.0" (85 x 129 x 126mm) and weigh less than one pound (0.45kg). DS Meters are completely self-contained. The built-in cell is automatically temperature compensated from 50° to 160°F (10° to 71°C). Self-conditioning of the built-in electrodes occurs each time the button is pressed with a sample in the cell cup. This ensures consistent results each time. By using an RE-10 Range Extender (see W3800-1)), the maximum range of most meters (except W3760-4) may be increased ten times. A 9-volt battery good for at least 2000 tests, or one-year shelf life powers these meters.