Hah! I'm sure people would wonder about mine too, but these things are sort of collateral damage. I'm in the middle of a multi-day cleaning frenzy, and I wanna know if I should be keeping them.
I have too many machines to manage, I asked for a bunch locally (so I could rehab them (for the practice) and try to donate them to places), and got them, so now it's cleanup time. If I can re-home some of this stuff with machines it belongs to, it cleans up for me as well as manages to get the parts back into use.
And,.. I'm more than a little OCD, and it's clutter.
The round thumb nut is about 2/3 the size of a dime and yes, solid metal. The grommet is approaching the size of a quarter...