The HM EC-3 dual-function testing pen precisely measures electrical conductivity and liquid temperature for daily and commercial water quality monitoring, calibrated in factory with standard 1413µS KCl solution and supports manual recalibration with a screwdriverHM Digital™. It covers a wide EC range from 0–9990µS/cm with graded resolution, paired with built-in ATC auto temperature compensation from 1–50℃ to eliminate temperature-caused reading deviation, delivering steady ±2% testing accuracy. Equipped with a large clear LCD screen, it features handy data hold to lock values, 10-minute auto shutoff to extend battery lifespan, and a low-power reminder for convenient operationHM Digital™. Made of durable light ABS plastic with compact pen-sized design, it comes with a belt-clip vinyl storage case for pocket or toolbox carry and full probe protection. Suitable for hydroponic cultivation, aquarium maintenance, drinking water filtration, swimming pool care and industrial wastewater sampling, this cost-effective tester works perfectly for home growers, lab technicians and water treatment workers. It includes matched LR44 button batteries out of box for instant use.