1/4"-hole thermocouples are held in place by a bolt to measure surface temperatures.

Item: Ring Thermocouple
Grounded / Ungrounded: Grounded
Thermocouple Type: K
Plug or Connector Type: 1/4" Ring Terminal
Insulation: Fiberglass
Lead Length: 4 ft.
Error Accuracy (Deg. C): +/-2.2 Below 293
Error Accuracy (%): (Over 293 C) +/-0.75
Temp. Limit (Deg. F): 900
Thermocouple Element: 20 AWG
Construction: 1/4" Ring Attached to Thermocouple Wire