The Oakton WD-56700-15 pH/ORP/Temp Controller is a rugged microprocessor based instrument assembled in a watertight 1/8 DIN case, designed for use in laboratories and process control applications. The system displays pH or ORP or Temperature and relay status in one large LCD screen. The pH/ORP 220 is equipped with 2 control relays and an isolated 4-20 mA analog output. All control relays are programmable and hysteresis driven.