The SpinFaktor HG Heavy Gravity featured rim weighting like YoYoJam's composite body models, but was an all plastic model. The rim plastic was made much denser than the rest of the yo-yo by adding heavier particles to the mix.
YoYoJam released these in fall of 2005. They were part of a limited test run, and only about 80 were made. The HG XTra is the same shape and size as the standard HG, but was much heavier.
