THIS THERMOMETER INSTALL is not from any brew store. I have a whole thread here on this system, but the quick and dirty is this.
Drill a 1" dia hole with a hole saw
Plug it with a #5.5 SOLID stopper
SHOVE a probe thermometer through it... (after drilling a small hole through it)
Seals perfectly, it costs maybe $10 total...
Get the thermometer at Target, get the stopper from anywhere, and get a drill from your neighbor. No need to waste $$$ on an overly complicated contraption and then also paying shipping.
Stay tuned for my COOLER HERMS heat exchanger build for this system as well...