Performance indication: Basic functions: * Switch / lock button (ON / OFF / HOLD) Function: Power on: in the shutdown state, press the button, you can boot. Automatic shutdown: 5 minutes after the use of automatic shutdown. Manual shutdown: press the button 3s to shut down continuously. * Press the function key to display the test water quality conductivity us / cm value, and then press once to display the Celsius temperature °, then press once again to display the Fahrenheit. The function selection button (MODE): the default display test water quality total solid dissolved amount ppm; Temperature °; then repeat the cycle to display the above. * CLEAR key function: clear. Clear the lock read and re-test. * Automatic test and lock reading: clear after the insertion of water can be automatically read, according to the different water quality shows the corresponding TDS value or conductivity us / cm value. And then automatically locked. * Scale function: according to national standard scale. And with appropriate reference to international practice. Direct drinking water warning with reference to national standards using TDS = 40 for the dividing line. Less than 40 show green backlight, for qualified straight drinking water, more than 40 show red backlit, for non-direct drinking water. * Backlight function: the use of low-power backlight, easy to night and light dark place for testing use. At the same time as a direct drinking water to determine the show. * Large screen display: the use of high distortion STN thin liquid crystal, display 4-digit value and the corresponding physical unit. TDS read range: 0-9999, identifier; Supply voltage: CR2032 battery, DC3V; 230mAh. (Not included) Test range: TDS: 0 to 9999 ppm. Accuracy: ± 2% F.S 6. Temperature test range: 0 ~ 99 ° (Fahrenheit for 32 ~ 212 °), acc