If you have a CTC or similar printer, you will find that these need an insulated thermocouple for the extruder - should the original fail.

The cheapo ones from China are not insulated and do not work. I have however modified a few for my printers and have about 5 or 6 available if anyone needs one.

I am based in the UK and will sell them including postage within the UK for 5 each or 2 for 8.

Please let me know if you are interested