Using a special magnet, the Pro Auto-Cal offers simple, automatic calibration and external testing without removing the cover of the unit. With unsurpassed sensitivity and fail-safe performance, the Pro Auto-Cal allows for temperature-stable calibration and an adjustable time delay of up to 10 seconds to allow for settling of material--virtually eliminating false alarms. Optional sensing probes including Delrin or Teflon-sleeved, bare, food grade, or flush mount. A variety of solid and flexible extensions make this capacitance probe suitable for many applications.