Features: Just dip in the meter, stir, and get your results in seconds. It's compact and doesn't require any maintenance. The TDS digital water tester can accurately and quickly check the total dissolved solids, soluble salt content, and ionic-organic matter. In addition to known reliable mineral water, other purified water sources should be tested for purity to help protect the health of children, the elderly, and pregnant women. Small size and lightweight design, similar to a pen, makes it easy to carry and convenient to take in your pocket when going out. Power supply: 2x1.5v button battery (included). Package Includes: 1x Water Quality Tester Specifications: Material: Plastic Package size: 160x35x25mm / 6.3x1.4x1in Power supply: 2x1.5v button battery (included) Note: 1. Remove the pen cover and turn on the ON/OFF switch. 2. Insert the pen into the solution to be tested. The solution level should not exceed 4cm from the bottom of the pen. 3. Gently stir the pen in the solution several times until the reading stabilizes. TDS measurements are affected by temperature, so temperature compensation may be required for accurate results. Press the HOLD key to manually lock the reading. To retest, press the CLEAR key to reset and then test again. Press the MODE key to select different test functions. 4. After use, wipe the tip of the pen with a clean cloth and return it to its holder. 5. Hold down the ON/OFF key for 3 seconds to manually power off the device. Please allow 1-3cm error due to manual measurement. Please note that the actual product color may vary slightly due to differences in monitor displays.