[Auto Calibration] We strictly test each PH test pen in order to make sure everyone you purchase our PH meter pen can read accurate PH level. Besides, you can press the button CAL or immersing the electrode into the solution to calibrate the digital ph meter. [Sensitive Electrode] pH tester has a sensitive electrode sensor to read accurate ph levels. (Accuracy range: 0.01) You can test the PH value for any 0-16 PH liquid. [Auto Temperature Compensation] This ph meter built-in (ATC) automatic temperature compensation, it can accurately determine the pH value of the sample in a range of 0C - 60C (32F - 140F). So you don't worry about temperature of the sample. [healthy Lifestyle] pH meter can tell you the acidity and alkalinity of water ensure health of drinking water and keep it in perfect pH balance, pH value of drinking water range of 6.5-8.5 to meet the EPA standards. You can test drinking water, swimming pools, aquariums, hydroponics, wine and beer and so on. [Notices] After placing the pH acidity tester in water about 1 minute you can get the most accurate measurement data. In addition, if the water surface shakes will be affects measurement results. Please wash and dry the water in the PH meter after use, otherwise they will rust.