TDS: 0 - 9990 ppm (parts per million) Conductivity: 0 - 9990 μs/cm Celsius: 0.1 - 50.0°C Fahrenheit: 32.0 - 122.0°F Accuracy: ±2% FS Weight: 70g Size: 16.2* 2.9 * 1.5cm / 6.4 * 1.1 * 0.6in Operating environment: 0-50°C CR2032 button batteries Take the pen cover and turn on the ON switch; Put the pen into the test liquor, the height liquor should not exceed 4cm; Shake the pen several times until the reading result is stable; Dry the tip of the pen with a dry cloth and put the pen back into the pen holder after use. Please note: Factory calibrated, no need Avoid putting the whole pen into liquor; Avoid high temperature and direct sunlight; Avoid impact, heavy pressure, and etc.