pH MODE : Up to 5 points push-button calibration with auto-buffer recognition. Selectable pH buffer standards, (USA, DIN, NIST, User-defined) resolution (0.1,0.01,0.001pH) temperature units (°C or °F) Automatically calculates and displays electrode slope that helps you decide whether to replace pH electrode. Calibration due reminder prompts you to calibrate the meter regularly. ORP MODE : Absolute or Relative mV measurements provides accurate ORP measured value. 1 point offset calibration allows user adjusts displayed value to a known standard. CONDUCTIVITY/TDS/SALINITY/RESISTIVITY MODE : Up to 5-point push-button calibration allows user to uses customized calibration solutions. Default 10S, 84S, 1413S, 12.88mS and 111.8mS) Adjustable TDS conversion factors, cell constants, temperature coefficients and normalization temperature. (20°C or 25 °C) allows user selects linear or pure water temperature compensation modes. In salinity measurement modes, selectable practical salinity (PSU) or seawater measurement standards. (ppt)µµµ AUTOMATIC TEMPERATURE COMPENSATION : Using the supplied temperature probe, the temperature value is displayed on the screen. The meters provides manual or temperature compensation mode for optimum accuracy under variable temperature conditions. VIEWING OF ELECTRODE SLOPE : After calibration, the percentage slope of the electrode is displayed before the meter returns to measurement mode. Per the slope value, user decides whether the change the electrode. MULTI - POINT PUSH - BUTTON CALIBRATION : The meters have multi-point calibration mode. choose calibration and immerse electrode into indicated calibration solution. press ENTRY and meter is automatically calibrated. SAVE AND COMMUNICATION INTER FACE : The meters all have real-time date / clock stamps. The memory stores up to data set. Press the SAVE Key to store the current measures values and it automatically generates a serial number with the data and time. This data can then be set to a computer via the USB port