The ORP-200 is ideal for all ORP testing, including antioxidant measurement, water purification applications, ionizers, agriculture, aquariums and aquaculture, chlorine monitoring, cooling tower disinfection, environmental testing, fruit and vegetable washing, hydroponics, metal finishing, ozone system monitoring, pharmaceutical and medical applications, pools and spas, pulp bleaching, vineyards, wineries and water treatment. The ORP Meter measures oxidation reduction potential (Redox) and temperature. The ORP-200 meter has an auto-ranging calibration with digital fine tuning. This Waterproof ORP Meter includes storage solution in a sponge embedded in a clear cap. The ORP 200 Meter comes with waterproof housing (IP-67 rating). The ORP-200 Meter has simultaneous temperature display. This ORP Meter can be calibrated digitally (push button). The meter has auto-off function, data-hold function and low-battery indicator. Display: large and easy-to-read LCD screen includes simultaneous temperature reading. This ORP Meter has a replaceable sensor SP-O2. Factory Calibrated: The ORP-200 meter is factory calibrated to +92 mV. The meter can be easily recalibrated with digital calibration using the push buttons, rather than a screwdriver. The Meter also includes a cap, batteries, and lanyard. Always make sure your sensor is kept in an electrode storage solution. If dry, refill the cap with the OP-STOR storage solution.