Cone Art Porcelain Protection Tube (for thermocouple)Cone Art Porcelain Protection Tube (for 6. 5" thermocouple) Thermocouple protection tubes are a fantastic way to protect Type K thermocouples. Made of a high temperature ceramic material, these tubes encase your thermocouples and give dual protection. * It should be noted that an offset of approximately 25 degrees F will need to be programmed into the controller to account for it being slightly cooler inside the tube than exposed in the kiln.