YSI Quatro [605790-20] Cable Assembly (ISE/ISE/DO/Cond) with Temperature/Conductivity Sensor, 20m. The YSI Quatro is a new 4-port cable and bulkhead for the Professional Plus handheld instrument making it possible to measure conductivity and temperature, dissolved oxygen, and your choice of any two ISEs among pH, ORP, ammonium, nitrate or chloride. All sensors are rugged and designed for true field work to reduce the overall cost of ownership.