Features: 1. Large LCD screen makes results easy to read. 2. Automatic calibration is more convenient, removes the need for any other tools. 3. Simple to use with accurate and fast results displayed. 4. ATC Automatic Temperature Compensation accounts for temerature changes automatically. 5. Full measurement range of pH 0-14, 0.1pH resolution. Notice: 1. Actual color may be slightly different from the image due to different monitor and light effect. Please allow minor deviation due to manual measurement. Specification: Measuring range: 0.00-14.00PH Accuracy: ± 0.2PH ± 0.1PH 20 degC Resolution: 0.1PH Working temperature: 0-50degC Battery: 3X1.5V battery Not included Dimensions: 142mm L × 29mm W × 15mm H Professional tips: 1. The thinner the glass of the glass electrode, the higher the accuracy 2. Advantage of calibration powder: The calibration powder has a shelf life of 5 years, and even if the calibration solutions is not opened, moss will grow after only one month. In addition, the standard requirement for calibration is that it needs to be calibrated against 250ml of distilled water sold in supermarkets The bottle is only about 20ml, which does not meet the requirements at all, and when the pen is placed in the bottle for calibration, the bottle mouth is too small to put in. The opened calibration solutions can only be placed for 15 days before it will be invalid, so the bottled calibration solutions is prepared. We don39;t recommend it. There is no pH pen that does not need to be corrected, but the correction is very simple The pH meter must be recalibrated under the following conditions: 1. It has been used or placed for a long time after calibration; 2. The electrodes are used very frequently; 3. The measurement accuracy is relatively high. 4. No calibration is needed to buy the new pen Calibration of pH meter: 1. Rinse the calibration powder with 250ml of distilled water or purified water. Immerse the pH electrode in a mixed phosphate standard buffer solutions with a pH of 6.86 or 4.0 and shake gently. 2. With a small yellow screwdriver, turn the left and right of the pH pen to adjust the potentiometer until the displayed value matches the pH value of the standard buffer solutions at ambient temperature of 6.9 or 4.0. Do not soil the liquid. Seal it with plastic wrap after calibration. It can be reused. After calibration, wash it with pure water. If you don39;t use it frequently, you can calibrate it once in 3-6 months How to maintain the pH pen: If you don39;t use it for a long time, you can soak the electrode of the pH pen in pure water in about halfs month and insert it in a disposable cup Steps: 1. Remove the protective sleeve. 2. Turn on the switch located on the battery compartment. 3. Insert the pH meter into the liquid to be measured until the liquid is immersed in the immersion line. If conditions permit, the solutions can be immersed in a position slightly higher than the immersion line. 4. Gently stir the solutions and wait for about two minutes. Read the displayed value. 5. After use. Clean the electrode. Turn off the switch. Put on a protective cover. Package List: 1 x pH meter