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