REED Instruments SD-4307 SD Series Conductivity/TDS/Salinity Datalogger Measuring Ranges: 200S, 2mS, 20mS, 200mS / 200, 2000, 20000, 200000 ppm / 0-12% (Salinity) Measures conductivity, total dissolved solids (TDS) and salt levels in water Automatic temperature compensation Real time datalogger with integral SD memory card (optional) Includes hard carrying case, probe and batteries