1.[Aplication]As a tool to improve the quality of life. Can be used to test drinking water, swimming pools, PH balance in an aquarium, RO system, spa, or hydroponics. All the environments that need to test PH values can use this tester to get accurate data. 2.[How to use calibration]Place the tester in a calibration solution. Press CAL for 3 seconds to enter the calibration mode, and press in turn to select the powders corresponding to 6.86, 4.00, and 9.18 to complete the calibration. 3.[Easy to use]turn on the switch, place the probe into the water, and stir (make the small glass ball fully the liquid) and the value can be read when the value is stable. 4.[Automatic Temperature Compensation-ATC]There is no need to care about the temperature of the liquid being measured. The PH meter has an automatic temperature compensation function. 5.[Mini Size]The mini size of the pH meter allows you to easily put it in your pocket, so you can take measurements anytime, anywhere. It can help you to make a pH test anywhere, you just take it to the pool, on a trip, to the beach, camping, etc. 6.[pH tester]Full measurement range of pH 0 - 14, reliable and quick readings. The technical definition of pH is that it measures the activity of the hydrogen ion (H+) and is reported as the reciprocal of the logarithm of the hydrogen ion activity. Therefore, water with a pH of 7 has 10-7 moles per liter of hydrogen ions, whereas a pH of 6 has 10-6 moles per liter. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.