What are these?

[George S.]

Picked up a analog DC Millivolt meter just like I used in shop class long ago. Can't remember what the red and green accessories are used for.
Adapters for measuring home heater thermocouples?
Can't find anything on the web or even a Google Lens search result that matches.
It's a solid and accurate little unit.

 

[Pure_Brew]

Kinda looks like coax in-line protection. Ham radio maybe?

 

[George S.]

Think they were used on a now long gone natural gas, pilot light, thermal couple, valve and relay heater assembly.
Oh well. I'll keep them in the case as a curiosity.