NEW FEATURE ADDED IN 2012 - The TDR family of meters now includes the option to perform a calibration on an individual meter. The calibration is done in 2 media; air and distilled water. This new feature took effect with firmware version 6.5 and is included with units shipped after January 1, 2012. Meters with firmware versions earlier than v. 6.5 can be upgraded by purchasing and installing an updated microcontroller chip (Item #CHIP-TDR3. See Calibration Feature of FieldScout TDR Meters for more details.