Thermometer probe belt device...

[An Ankoù]

https://www.geterbrewed.com/3-8-thread-weedless-thermowell-stainless-steel/Just drill a hole and fit one of these.

 

[sifty]

I also use a clear plastic fermzilla pressure fermenter though. Not so keen to drill holes in that...

 

[dcbrookes]

Before I got thermowells, I used to use a length of pipe insulation (the stuff like silver mylar with a bubble wrap core - about 40mm wide). A couple of bits of self adhesive velco fixed it neatly and it held the probe snugly against the fermenter.

 

[gingerneil]

https://www.geterbrewed.com/3-8-thread-weedless-thermowell-stainless-steel/Just drill a hole and fit one of these.

Or just use an ispindel?? :)