If it is on the exterior, it has no contact with the
juice, at least IMO...
But I have a fetish for brass, copper, pewter, and the like, when they are decorative, or air hole controls in drippers...each to his/her own though.
Have never looked for SS rings but try FT, as they have "Magmas", and bits and bobs. I saw another site with the same sort of stuff in the US. Try a google for
vaping spare parts or ecig spares...

Search engines can be useful, sometimes but not always....
