Steps for use: Before use, remove the electrode protective sleeve; Press the button and insert the electrode into the solution to be tested; When the value is stable, press the HOLD key to remove the reading; After reading, press the button, dry off the electrode and insert the electrode protection sleeve into it;Instrument features Lock function: easy to read and record, the instrument locks the reading; 5 minutes automatic power off function, the battery will not run out; TDS and conductivity switching: The meter shows the TDS value at the factory. If you want to measure the conductivity of the solution, gently press the SHIFT key, the meter switches automatically; The automatic temperature compensation instrument has an automatic temperature compensation function in the measurement mode; Temperature switch: Press the SHIFT key twice in a row to switch between degrees Celsius and Fahrenheit, the meter is standard in degrees Celsius; Maintenance: Keep the electrode clean and cover the electrode protection sleeve. If it is not used for a long time, please take out the battery How to calibrate the TDS meter: 1.In the water, hold the temp button for 3 seconds, release your hand when the font flashes. 2.Press the temp is "+", hold is "-".3.Adjust the value.4.Press the temp button for 3 seconds. Calibration is complete when the font stops flashing. Please note: Do not submerge the entire TDS meter in water or submerge above the maximum immersion level (approximately 2" - see manual for additional information). This device is not waterproof and will be damaged if water enters the device. Specifications: 100% new brand and high quality Product name: Water Purity Tester Material: plastic Color blue Conductivity: 0-9990us/cmTDS: 0-5000 ppmCelsius: 0.1-80.0CFahrenheit: 32.0-176.0FAccuracy: 2%Size: As picture package contains: 1pc* Water Purity Tester Note: 1. Due to the different monitor and light effect, the actual color of the item may be slightly different from the color shown in the pictures.2. Please forgive 0.39in-1.18in measurement deviation due to manual measurement.