The technical description for these is "2-piece internal double beadlocks".

These pictures are 37x12.50-16 tires that weigh 75lb on a 16x8 wheel for a total weight of 140 lbs each. Only 10 oz of Dyna Beads was used per tire.

Pictures courtesy of http://www.pavementsucks.com

This shows the sophisticated device used to spread the rim pieces.

Now we simply pour in the Dyna Beads!

The result was a vibration-free ride, tested to 75 mph.