Advanced 3-in-1The smart pen combines TDS, EC and thermometer to improve accuracy. With automatic temperature compensation and a measurement range of 0-9999 ppm +/- 2%, it is a very handy device. Easy to UseThe TDS meter will automatically lock in seconds, and the TDS tester will automatically shut down after 2 minutes of non-use to save battery. With hold function, the measured value can be saved for easy reading and recording. Wide Use, High Precision ElectrodeTDS Water Quality - Great for drinking water, laboratory, hydroponics, aquarium, swimming pool, RO/RD system, food and beverage, whole house filtration system water, water tank, spring water, ppm test. The TDS water quality tester is equipped with a high-quality titanium alloy probe for fast and convenient testing. Put the probe in the water and the LCD will display accurate results within seconds. Measurement RangeEasy-to-read LCD screen with auto-off function prolongs battery life, easy to use, large backlit color-coded display is helpful, easy to read without glasses. It is lightweight and easy to carry in a pocket when working in the garden. seems to be reliable.