4 in 1 PH tester: A very complete kit to check the quality of your water, from the tap, to recovery, through the aquarium or the swimming pool. TDS / PH testers have small dimensions and low weight as a pen, pH meter for drinking water, beverages, for aquariums, hydroponics, swimming pools.pH- Ease of use meter: TDS water freezes the measurement result when you press the "HOLD" button and automatically shuts off after a few minutes of non-use. And these 2-in-1 pH meters and TDS meters are also ideal for home testing.High Accuracy: The numbers of the pH meter range from 0.00 to 14.00 (PH), while the EC and TDS digital meter numbers range from 0 to 19,990 ppm. Use a digital meter to get precision numbers instead of comparing color with pH test paper, avoid making inaccuracies due to different light, also helpful for those who are low in color.Easy Calibration: The pH tester self-calibrates at three points (6.86 and 4.01 point calibration). You don't need any tools, just dip the pH meter electrode into the solution. Press "ON/OFF" to open the electronic pH meter, shake lightly and wait a few seconds until the readings stabilize.