[Automatic Calibration]Every Preciva PH tester is calibrated before it was sent to our customers, no need to calibrate again. You can calibrate it every two weeks if it is used frequently, and once a month if not frequently. [Automatic Temperature Compensation]Provides full PH 0-14 measurements with temperature compensation which will make the result more accurate. After testing strong acid or strong alkaline liquid, please wash the probe with distilled water before measuring other liquids. [Easy to Use]Just need to see the number on the digital display of the PH meter when you are testing the liquid, more efficient and time-saving. If your reading is not stable, please wait for about 1 minute for the liquid to settle. [Convenient to Carry with]This hydroponic ph pen is designed based on the handy size that is ideal for carrying in your pocket and test the PH no matter where you are. [Widely Application]Ideal digital pH meter for aquarium, fishing, swimming pool, student lab, tap water and other liquid. Note: The white matter that comes with the product belongs to the characteristics of the product itself. It is safe to dissolve the auxiliary measurement when measuring.