Monsterpike,
Although the Shift and Gravity Shift share the same name, The Gravity Shift has a different core. The core is now smaller and more dense creating a lower RG. The shape of the core has also has been tweaked a bit.
Also, the cover is a new cover material called the R2X. This cover is designed to clear the fronts a little easier, and really read the mid lane. This new coverstock is also designed to not soak with oil as quickly, hence yielding a longer life span.
In my opinion, the Gravity Shift is more comparable to the Paradigm, or Domination. The Gravity is strong in the mid lane like the Paradigm, but with more backend like the Domination. The best of both of those balls.
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Tommy Gollick
Storm Regional/Pro Shop staff
Red Crown Pro Shop Harrisburg, PA
stormbowling.com