The HM Digital COM-100 is a professional IP67 waterproof 3-in-1 water quality tester that measures EC, TDS and temperature simultaneously for precise water monitoring. Built with advanced ATC automatic temperature compensation, it automatically offsets temperature interference to deliver consistent, error-free readings across all water samples. It supports dual TDS conversion scales (0.5 NaCl & 0.7 442) and multi-unit switching for µS, mS and ppm, meeting diverse testing standards. Featuring one-touch digital push-button calibration, users can easily recalibrate without extra screwdrivers. The large dual-display LCD shows real-time data, with data hold, auto power-off and low-battery alert for convenient field operation. Its durable sealed waterproof body resists splashes and submersion, paired with a long-life precision sensor probe. Ideal for hydroponics, aquariums, swimming pools, drinking water, RO systems and small water labs, this compact handheld meter replaces three separate single-function tools to simplify daily water parameter tracking reliably.