describe: Calibration method: long press CAL for 5 seconds to enter the calibration mode, and then press to select the powder corresponding to 6.86, 4, and 9.18 to complete the calibration. MINI SIZE: We designed the mini size pH meter to easily fit in your pocket and take measurements anytime, anywhere. Whether you're taking it to the pool, traveling, the beach, or camping, it's here to help you try it out. Household essentials: as a tool to improve the quality of life. Can be used to test pH balance in drinking water, swimming pools, aquariums, RO systems, spas or hydroponics. Basically all environments that need to test the pH value can use this tester to get accurate data. High Accuracy: The pH tester has a sensitive electrode sensor, just press "ON" and your results will appear on the screen in just a few seconds. Read accurate pH. The accompanying detailed manual will show you how to get the best accurate and stable readings. Automatic Temperature Compensation - No more need to care about the temperature of the test liquid, as the pH meter has automatic temperature compensation that adjusts for water temperature and water quality. Specification: Measuring range: 0.00-14.00PH Accuracy error: ±0.01PH Resolution: 0.01PH Working temperature: 0℃-60℃ Battery: 2X1.5V (LR44 button battery) Dimensions: 155mm×31mm(W)×18mm(H) Notice: The pH meter must be recalibrated in the following cases: 1. It has been used (or placed) for a long time after calibration; 2. Electrodes are used frequently; 3. The measurement accuracy is required to be high. Instructions: Cut the plastic bag, pour the powder into a 250ML volumetric flask, rinse the inner wall of the plastic bag with a small amount of CO2-free distilled water, pure water or neutral water with a pH value of about 7, and dilute to the mark and shake well. The shelf life of the powder is 2 years. As long as the calibration solution is not contaminated, it can be reused. The shelf life after adding water is about 6 months. After the calibration powder is mixed into calibration solution, follow the steps below: How to use the calibration solution: Wash the pH meter electrode with pure water (2-3 times) 1. Immerse the pH electrode in a mixed phosphate standard buffer solution with a pH value of 6.86 (25°C), and shake gently. 2. Press and hold the Xiaozheng button, don't let go after the value starts to jump, keep pressing until the value is displayed to 6.86, then let go after it stops 3. Rinse the electrode with pure water first, and then insert the electrode into the standard buffer solution of potassium hydrogen phosphazene with pH 4.00 for calibration. 4. After about two minutes. The displayed value should be within the allowable error range compared to the pH value of the buffer solution. The so-called two-point calibration is to use two kinds of calibration solutions to calibrate Generally, the calibration starts from 6.86. then using 4.00 Package includes: Detection pen*1