Anyone have a cue with this?...

[skins]

Aluminum buttcap bushing....

 

[SSDiver2112]

What are you trying to know with this question. Have I seen one before, yes.

Example: This Huebler I repaired has one.

 

[Birk1]

I had an old kikel with a metal ring to keep the bumper from expanding to prevent cracking the ivory buttcap. This looks like a Tasc, which does a similar thing. Nice cue.