Please note: The physical item may have a slight color difference due to lighting and screen display variations, which does not affect the use. Thank you. [LCD BACKLIGHT]: Our TDS water meter is equipped with low-power backlight technology, making it easy to test water at night or in dark environments. The red backlight (ppm > 40) indicates that the current water quality is not ideal and not suitable for drinking. [3-in-1 Test Function]: Featuring advanced 3-in-1 technology (TDS, EC, Temperature), this conductive pen tester measures TDS, EC, and water temperature. The TDS range is 09990 ppm, and temperature readings can be displayed in both Celsius and Fahrenheit. Simple and easy to operate: Turn on the TDS meter, gently stir in the water, and within seconds the LCD display will automatically lock the reading. The device automatically powers off after 2 minutes of inactivity to conserve battery life. Instructions for use: 1. Remove the pen cover and press the ON button to turn on the tester. 2. Insert the pen into the solution to be tested, ensuring the liquid level does not exceed 4 centimeters from the bottom of the pen. 3. Gently stir several times in the solution and wait for the reading to stabilize within a few seconds. 4. After use, wipe the tester dry with a cloth and replace the cap. Ideal for various water quality testing applications including water purification, aquaculture, hydroponics, swimming pools, and water treatment systems. Test tap water, filtered water, distilled water, bottled water, well water, and cold water. A convenient and essential tool for water quality monitoring. Color: Black + White Material: Plastic Package Contents: 1 x TDS Meter Note: Light reflection and different displays may cause slight color variations between the image and the actual item. Measurement error is +/- 13 cm. Only the items listed above are included.