4-in-1 PH Tester: A very complete kit for checking the quality of your water, from tap water to recovery, including aquariums or swimming pools. The TDS / PH testers have small dimensions and light weight like a pen, a 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 pH meter numbers 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