SMART pH sensors store calibration information and upload it into the instrument. One big advantage is that these sensors can be calibrated in a laboratory or a maintenance shop. This is a huge advantage for those of you who are located in locations with extreme weather conditions. When the sensor needs to be installed or replace, just calibrate in a comfortable environment, then installed in a remote location. Information uploaded into the instrument includes slope, glass Impedance, reference offset, and reference impedance. Watching the trends of these variables will help indicate when it is time to clean, calibrate, or replace the sensor.