For your h/w tank, or boiler. Just make sure 2ft is long enough to reach where it mounts by the pilot light.
Regular price is ~$10-11 for Eastman, Honeywell thermocouplers from HD, CanadianTire, Rona, etc.
https://www.amazon.ca/gp/product/B00IV9 … UTF8&psc=1
Amazon product: Eastman 60038 Thermocouple, 36″ Length, Stainless Steel
We have a very old, but excellent natural gas furnace, and it needs a new thermocouple every year (sometimes 2 years). It was great finding this thermocouple on Amazon for such a good price. Now, we will be changing the thermocouple every summer when we shut down our furnace for maintenance. Saves having a “heating emergency” in the middle of winter. Good brand at a great price – recommended. 🙂