Wouldn't bowl without one. Used to have some hand pain across the top of my hand. Put one of these on and I have never had a problem again. From what I know, the little ball bearing actually takes pressure off of your wrist. I have read it can take off 10% of the pressure, thus the F10X I would guess.
I have even sold some to people who type a lot and are bothered by carpal tunnel or however you spell that. They love them too.
Tyson
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Who needs a 300 or 800, when I have a 294 and a 295!?!?!