【Three-in-one Test Function】 Advanced three-in-one guide pin (TDS, EC, temperature), the tester can not only detect TDS but also EC and temperature in water. The ppm meter has a range of 0-9990 ppm and the temperature also supports two reading modes: Celsius and Fahrenheit. 【LCD Backlight】 The TDS water meter is equipped with low-power backlight technology to easily test water at night or in dark places. It can also be used to differentiate drinking water from non-drinking water. The red backlight (ppm > 40) reminds the user that the current water quality is not ideal, indicating that it is undrinkable. 【Simple and Convenient Operation】 Simply turn on the TDS water meter, gently stir the water, the LCD screen will automatically lock in seconds, the TDS tester will automatically turn off if it is not operated for 2 minutes to save battery life. 【Application】Ideal for tap water quality testing, home water filtration equipment, aquariums, swimming pools, hydroponic, colloidal silver,