The Milwaukee CD601 digital electrical conductivity (EC) Pen is designed for aquariums, aquaculture, pools, water conditioning and many other applications. The CD601 helps you make sure that your water has the right amount of nutrient to help keep fish tanks healthy or helps you keep your filters up-to-date and clean for water filtration. Keep EC in your target range to help your achieve better results.Milwaukee digital Conductivity Tester CD601+ measures microSiemens (uS/cm) direct and with automatic temperature compensation+ ideal range for aquariums (0 to 1990 uS/cm)+ units in uS/cm are easily convertable to (ppm)+ factory calibrated with the ability to recalibrate if needed+ automatic Temperature Compensation (ATC)+ 350 hours continuous use (4 x 1.5V batteries included)+ simple one point calibrationtechnical data Milwaukee digital Conductivity Tester CD601Range: 0 to 1990 uS/cmResolution: 10 uS/cmAccuracy: +/- 2% Full Scaletypical EMC Deviation: +/-1% Full Scalecalibration: manual,