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.< p>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.