[less than useful post, but what the hell]  I'm curious about these too, but haven't asked because I can't stop giggling.  When I see them, I can't stop thinking they look like little rubbers. silly and strange? yeah.

So... do they work?  (as vibration/sound dampers)    :)

It's interesting that the original poster was using them, but didn't offer an opinion either way!

I had one pair of input tubes that came to me from Steve with orange isolator rings installed. I used them with and without the rings and honestly couldn't say they made a difference. I use Herbie's Audio tube dampers and feel they do make a subtle difference, I can usually tell if they are on or off. . . .