Auto CalibrationEach pH tester is calibrated before sending to our customers, no need to calibrate again. It can be calibrated every two weeks for frequent use and every month for infrequent use.Automatic Temperature CompensationProvides full PH 0-14 measurement and temperature compensation to make results more accurate . After testing strong acids or strong alkaline liquids, rinse the probe with distilled water before measuring other liquids. Easy to UseWhen testing liquids, you only need to look at the numbers on the digital display of the pH meter, which is more efficient. and time saving. If your readings are unstable, wait about 1 minute for the fluid to stabilize. Easy to CarryThis hydroponic ph pen is designed based on the convenient size, its perfect to carry in your pocket, you can test ph wherever you are. Wide Applications Ideal digital pH meter for aquariums, fishing, swimming pools, student labs, tap water and other liquids. Note: The white substance supplied with the product is a feature of the product itself. Dissolution-assisted measurement is safe when measuring. This PH pen has an accuracy of 0.01 and comes standard with 2 packs of correction powder, screwdriver, plastic case.