Hey jedi,
The original suggested difference from Vise was 2 sizes but it can vary depending upon your original gripping holes. Even though we use a standard 31/32 bit, all these bits can vary in true diameter where some become smaller with each sharpening (as mine have).
With this said, if your driller doesn't sand each hole after drilling to fit a grip "loosely", they can compress the grip which causes for different grip sizes to be utilized for the individual bowler. This is another reason why bowlers may notice that some grips (even though they're the same size) may feel tighter from one ball to another. Plus the fact of having slight variances in grips from being mass produced.
I'd recommend to try a couple of different sizes to see which one you are most comfortable with. Just bear in mind that with Vacu, there will be no pressure around the grip to change its size so whatever feel you get while trying them, this is the feel you will get in the ball as well. Hope this helps some..
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Rick Leong - Ten Pins Pro Shop
Tag Team Coaching - Co-Founder
"El" Presidente of the Legion
