High-precision thermal sensor G1 / 4 inch thread . Can directly into a thread of an expansion tank , eg Coolplex , aluminum tube or Bullseye be screwed and sealed with a durable O - ring from . The shaft is knurled , which facilitates screwing in by hand , in the area of the sensor head , the residual wall thickness is reduced to <1 mm , which enables quick and precise measurements . It is universally applicable to the displaced persons in the shop equipment .