"No way that I'd pay $30 for a tube damper. I have used o-rings for years. If you want to experiment, you can fabricate couple of the halo style very easily. I can't see any advantage there; it doesn't really add mass, so it doesn't seem like it would fundamentally change the resonant frequencies or damping vs an o-ring or two. I would like to think that if any sort of tube damper, whether weighted or not, really made a huge improvement in sound, it would be standard equipment inside of high end tube amps such as those by ARC. Most companies that use anything, use an o-ring or a type of wider band that is basically a heavy, silicone grommet. It would become rather economical to add a more advanced type if it made a significant difference, due to the scale of production. The next time that I get around to it, I'll probably look into some larger bands rather than using a couple of o-rings myself. Not sure that there would be a sonic difference but it will only be a few dollar investment for a set."
I tend to agree with the above.