Milwaukee Instruments EC60 Waterproof 3-in-1 EC / TDS/Temp Tester with Replaceable ProbeThe Milwaukee EC60 PRO Conductivity Tester is designed for hydroponic and other growers to help you make sure that your plants have the ideal amount of nutrient avaiable. Keep EC in your target range to help your achieve better results.Features:Measures conductivity and TDS with automatic temperature compensationIdeal range for hydroponic and other growers (0.00 to 20.00 mS/cm)Units in mS/cm or ppt easily convertable to ppmFactory calibrated with the ability to recalibrate if neededReplaceable electrodeFully waterproof to IP65Approximately 100 hours of use (4 x 1.5V batteries included)