Description: HOW TO USE: Turn on the power switch, unplug the black head cover, insert the probe into the water to be measured, wait for the value to be stable, press the hold lock to take it out. DISPLAY: screen display, you can clearly see the data, easy to use. WATERPROOF DESIGN: Waterproof can be used with confidence and can be used for a long time. APPLICATION: Water quality testing pen, fast quality analyzer, suitable for household, industry, water plant, , etc. ACCURATE: Precision probes measure water quality more accurately. Specification: Measurement Accuracy: 2% Power Supply Voltage: 3v Resolution: 1ppm Size Chart: 2.5cmx13.4cmx1.4cm/0.98inchx5.28inchx0.55inch Package Includes: 1 Water Quality Test Pen Note: 1. Please allow slightly error due to manual measurement. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. 3. Wish you a wonderful on line shopping!