Measures Dissolved Oxygen concentration/saturation, pH, mV, Conductivity, TDS, Salinity, Resistivity and Temperature Automatic salinity compensation and manual barometric pressure compensation for DO measurements One button pH calibration (4, 7, and 10pH) Choice of 3 point pH calibration for better accuracy One point Conductivity calibration automatically recognizes 8 calibration solutions from USA, Europe and China series Automatic Temperature Compensation (non-linear compensation for purified water &lt,10µS/cm to improve measuring accuracy) Memory stores up to 400 readings with series number, measured value and temperature Large blue backlit dual LCD display Auto power off saves battery life with disable function Waterproof housing > Each Unit Includes DO probe pH/mV/Temp electrode Polymer Conductivity cell pH and Conductivity calbration solutions Batteries Hard carrying case