Replacement Probe For Ranco Digital Temperature ControllerIn case yours got too close to the flame on your brewing system. Probes can also be damaged by kinking which will cause a controller to give an inaccurate, high, reading. This is a replacement wire and thermistor for our line of Ranco controllers. The sensor probe is 1 4 in diameter and works well with the Stopper or Coupler Thermowells. Temperature Range of 30 to 220F. 8 ft. long. Probes are water resistant, but not water proof.