Milwaukee Instruments, MW605, Waterproof Galvanic Dissolved Oxygen Meter with Automatic CalibrationFeatures:Fast, easy-to-read results with large digital LCD readout.Galvanic probe means no conditioning time.Repeatable, accuracy to ±1.5% of reading.Water Proof IP 67 Rated.Lightweight and portable.Simple 1 or 2 % saturation calibration points at 100% (water saturated air) and 0% (zero oxygen solution). Dedicated GLP key to store and recall data on system status.Logged data export via USB cable.Altitude and Salinity compensation. Automatic temperature compensation °F & °C.Uses MA860 (included) reinforced Galvanic probe with an oxygen-permeable polytetrafluroethylene (PTFE) membrane sensor.2 O-rings, membranes and one protective cap included.10 feet probe cable for extra flexibility when testing.3 x 1.5 volt akaline AA battery (battery included) aprox. 200 hours of battery life with continuous use with low battery warning.The Milwaukee MW605 MAX Galvanic Portable Waterproof Dissolved Oxygen meter is one of Milwaukee's most popular meters with its reliable and fast operation as well as its accuracy. The Milwaukee MW605 MAX DO Meter is preferred by people looking for lab level accuracy without the cost. The Milwaukee DO Meter is popular with everyone from field biologists, educators, fish farmers, koi pond owners, water treatment plants and labs.Membrane Maintenance: For accurate and stable measurements, perfect condition of the membrane surface is needed. Protect the thin membrane from scratches, abrasion or contact with solids.If no measurements are taken for a few hours, protect the membrane with the plastic protective cap.If fouled, rinse it carefully with distilled or deionized water. If damaged, replace the membrane cap.