Rubber ring on my 70 Wag brake drums?

[thesaint]

I just bought a 70 Wag yesterday and I noticed that the outside of the front brake drum has a hollow rubbery ring attached to the outside of it filled with ball bearings or something. When I turn the wheel I hear the bearings hit together. Does anyone know what this might be? Thanks in advance for any advice.

[J20 project]

I seem to remember an attatchment they use to sell that was a wheel balancer. You put it on and while running down the road it balanced that particular wheel. Maybe??
J20

[jeepbob]

sometimes you would get a drum that squealed and the rubber ring would stop the squeal as it would dampen the vibrations that caused the squeal. I have not seen one in years as this is old tech.