Hanna Instruments HI98319 Marine Salinity Tester measures electrical conductivity (EC) to determine the salinity of natural and artificial seawater. It features a temperature compensated reading displayed on an easy-to-read LCD screen. Ideal for aquarium use and comes with calibration solutions. Pocket-sized and designed for ease of use, it includes a range of measurement capabilities including ppt, PSU, and S.G. with accuracy and battery life management features.