Tube rings for power tubes?

I recently bought a set of 6550 power tubes that came with tube rings. ARC has long been putting rings on their preamp tubes and there seems to be no question that doing so helps their sound. Has anyone had experience using rings on power tubes? Thanks.
I would suggest going to herbies
and asking Steve Herbelin what he thinks. I know him to be honest in every trans I've had with him.
His line level dampers are tremendous.
They CAME with tube rings? Are they the rubber (tube damper) type or the metal (heat radiating) kind? Where did you buy them? Did you ask the seller?

OK, I haven't heard of this or seen it -- ever. First, power tubes get so hot they'd burn/melt most tube rings, even the ones made with special silicon rubber. Two, good power tubes are not generally susceptible to microphonics like preamp tubes are, so damping is not really necessary.

The heat dissipating types (with metal fins) are not really any more effective than just leaving the glass exposed -- and could cause hot spots on the glass.
NSgarch- I'm a little reluctant to contradict you, since your posts are always thoughtful and (to me, anyways) very informative, but... I have some Herbie's on the 300b power tubes in my Cary 300 SEI. Now I don't push that amp very hard but there is no evidence of any discoloration anywhere, and I just checked the portion of the damper that actually touches the tubes. Maybe on a KT-88/6550 push/pull amp, but so far they are OK on my 300b amp.
FWIW, I use the herbie's tube dampers on the KT88's in my Cary SLI-80 with no problems. Herbie sells a version specifically for high-heat output tubes.
Another vote for Herbie, his rings are very reasonably priced and graded for tube heat. I have had no problems on my 845's and what gets hotter? I am sure someone will tell me.
Well if you guys say so ;--) I have to admit, it's been awhile since I've dealt w/ a lot of hot output tubes (16 x 6550's !) so maybe Herbie is able to offer something more heat resistant than used to be available.

But I still can't understand why one would need dampers on a power output tube -- i.e. unless the tube has internal damage, microphonics shouldn't be a problem in a reasonably vibration-free environment, and adding dampers to the glass envelope would impede cooling and create hot zones. So what would be the benefit? Am I missing something?
FWIW, I'm with Nsgarch's posts re his actual experiences and the requirements of power tubes, although I've never used Herbies and my power tubes were all common pentodes. No microphonic problems to solve in the first place.
Be sure to try them both with, and without the rings. I found that the life got sucked out of the music with rings on my EL34's.

Herbie's are probably the best out there for tube dampers that don't kill the music, at least on small tubes.

Don't take this as gospel, but I am pretty sure Herbie's offers a 30 day money back on all of their products. I know Steve does with his smaller tube dampers, record mats, etc. FWIW, I have his smaller tube dampers on my amp and really like them.