Product Description: Definition of Conductivity: Conductivity is the ability of a substance to conduct electric current. It is the reciprocal of resistivity. The unit of measurement is Siemens/cm (S/cm). 10^-6 of this unit is expressed as μS/cm, and 10^-3 is expressed as mS/cm. The 138 Series pen-type tester provides reliable measurements with simple and fast operation. This pen-type conductivity meter is compact and easy to carry, facilitating handheld measurements, with LCD display for reading measurements. This instrument is available in multiple colors and can be paired with calibration solutions and various packaging according to customer requirements.