[LCD backlight] :Our TDS water meter is equipped with low power backlight technology, which can easily test water at night or in a dark place. It can also be used to distinguish between drinking water and non-drinking water. The red backlight (ppm> 40) reminds the user that the current water quality is not ideal, indicating that this is non-potable water. . [Three-in-one test function]: advanced three-in-one (TDS, EC, temperature) conductivity pen, the tester can not only detect TDS, but also detect EC and temperature in water. The ppm meter range is 0-9990 ppm, and the temperature also supports two reading modes of Celsius and Fahrenheit. .[Simple and convenient operation]: Just turn on the TDS water meter and gently stir the water, and then the stable reading will automatically lock on the LCD within a few seconds; the TDS tester will automatically shut down after not using it for 2 minutes to save battery.. [Large capacity battery] : Equipped with 3V large capacity button battery. Can be effectively used for more than one year. . [100% Satisfaction Guarantee] : Thank you for supporting our products, we will do our best to provide you with satisfactory products and services. If you have any questions about our products, you can contact us, we will provide a 90-day money-back guarantee for illegal products.