Bluelab Conductivity Pen (EC or ppm) – Black Dog LED Europe
Amazon.com : Bluelab PENCON Conductivity Pen and Digital TDS Meter, Water Tester for Temperature and Nutrient (CF, EC, PPM 500, PPM 700), TDS Testing Kit for Hydroponic System and Indoor Plant Grow :
Bluelab Truncheon EC-meter
BlueLab Grower's Toolbox pH & EC meter kit - pH and EC testers
Bluelab Guardian Monitor pH Temp EC Conductivity Meter Hydroponic Blue Lab 9421024920081 | eBay
Bluelab Combo Meter Plus | Bluelab USA
Amazon.com : Bluelab TRUNV2 Truncheon Nutrient Meter, Digital Conductivity Tester in Water (Scales Include: EC, 500, ppm 700, CF, TDS) Tool for Hydroponic System and Indoor Plant Grow, White : Plant Germination