PH-097 Waterproof Automatic Calibration PH Tester Pen, featuring a large screen that simultaneously displays acidity and temperature, with an IP55 waterproof rating. 
All readings are automatically temperature compensated (ATC). The temperature sensor directly contacts the measured solution, ensuring accurate and fast readings. It adopts a two-point (pH4.00, pH6.86) automatic calibration method. During calibration, simply place the instrument in the corresponding standard buffer solution and press the CAL (calibration button). The instrument will then automatically calibrate the data. This function, compared to pH meters with analog circuits, offers faster calibration speed, more accurate data, and extremely simple operation, eliminating the hassle of adjusting potentiometers for calibration and repeated verification required by other devices. 
After turning on, the instrument will automatically shut down if no operation is performed for 4 minutes.