YSI ProQuatro [606969] Gal DO/pH/ORP/Cond 4m Field Kit with 2002 Galvanic DO, 1001 pH, 1002 ORP, Quatro 4m Cable and Carrying Case. The ProQuatro handheld multiparameter meter measures a variety of combinations of dissolved oxygen, conductivity, specific conductance, salinity, resistivity, total dissolved solids (TDS), pH, ORP, pH/ORP combination, ammonium ( ammonia), nitrate, chloride and temperature. In addition to its impact-resistant, waterproof case, the ProQuatro has features that make field sampling faster and easier: User–replaceable cables and sensors, real-time salinity compensation of DO measurements, built-in micro USB port for easy data transfer to flash drive and quick response times.