Bluelab EC Pen - Conductivity Pen for quick and accurate nutrient managementBluelab EC Pen Conductivity Pen for quick and accurate nutrient management Bluelab EC Pen Conductivity Pen The Bluelab Conductivity Pen (formerly EC Pen) is the ultimate handy solution for measuring conductivity and temperature. Using the same technology that made the bought the Bluelab Truncheon into worldwide fame, the EC Pen is quick and seriously reliable. The EC Pen demonstrates the conductivity (TDS PPM EC CF) of your aqueous solution to ensure