RCB10A Waterproof Conductivity Pen Type Meter. It is economic, but accurate, easy using. RCB10A Conductivity Pen Offering one of the best accuracies in pen-sized conductivity/TDS/SALT meters today, this10 series is replaceble, and large capacity electrode, cost down, life span long. Handy, IP67-waterproof and long-lasting, the pens are so light, they float! Applications• Water & wastewater ...