Core and layout of the ball controls the ball's motion, and the coverstock and cover prep controls the amount of hook. They are both very important, but the most important thing is matching the core/cover combo that will best suit your game, as well as finding a layout/surface prep that also matches up.
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*Erie Community College bowling*
Buffalo bowlers are the best all around in the country.
MoRich 4ever!!!! If you don't have one, try one. You won't be disappointed!!!