The Hanna Instruments HI 76301W four-ring potentiometric electrode is for use with the Hanna Instruments HI 8033 conductivity meter. The probe has a 1m cable with a DIN connector for attaching to the meter (sold separately).

Conductivity meters, also known as electrical conductivity (EC) meters, measure the ability of a solution or material to conduct an electrical current. This measurement helps determine if the solution is, for example, contaminated or contains too much saline. In general, pure solutions, such as distilled water, have low conductivity. More saline- or nutrient-rich solutions, such as seawater or fertilizers, have high conductivity. Conductivity measurements are often used with total dissolved solids (TDS) measurements, which are typically expressed in ppm (parts per million). TDS consist of dissolved minerals and salts. To determine the amount of TDS, conductivity is measured, and the result is converted to a TDS measurement. Different meters provide results for conductivity, TDS, or both, and the application determines meter selection. Conductivity meters are used in research laboratories and a variety of industries, such as water-quality testing, waste-water treatment, hydroponics, agriculture, aquaculture, and cosmetics manufacturing.

Hanna Instruments manufactures analytical instrumentation and supplies, including pH meters, electrodes, chemical reagents, and buffer solutions. The company, founded in 1978 and headquartered in Woonsocket, RI, meets International Organization for Standardization (ISO) standard 9001.