That’s what I like about websites like this. 45 years of tinkering and building engines and I’ve never seen these. Kinda reminds me of the bearing and gear temp sticks I used during my Millwrighting years. We had temp sticks that we would use that melted at different temps. (150-400 degrees) we used bearing heaters for new bearing installs and open gas burners we made for heating gears for rolls and lineshafts.