The product description must add water according to the required proportion, otherwise it will affect the accuracy of calibration and increase the error of calibration powder: pH standard solid substance. After adding water, it can be used. Suitable for calibrating any type of pH meter. Each small bag can prepare 250 ml of standard solution. Calibrate in the order of 6.86, 4, and 9.18. Reminder: PH probe is a glass product and a fragile product. Please don't touch anything. Once damaged and cannot be replaced, the probe must be protected. After use, gently absorb the moisture in the probe with a tissue. Opening the pen cover may cause the number to float, which is a normal phenomenon as the probe may come into contact with air and cause the pH meter to float. The tee has been calibrated before delivery, and the buyer does not need to recalibrate after receiving the goods. In the following situations, the pH meter must be recalibrated. 1. Long use time after calibration; 2. Regularly use special electrodes; 3. The measurement accuracy requirements are relatively high. Battery installation: If the backlight brightness significantly decreases or the display value is blurry, the battery needs to be replaced. When replacing the battery, simply remove the battery box and replace it. Pay attention to polarity. Standard configuration: 1XPH table.