The rule eliminating balance holes in bowling balls takes effect Aug. 1, the start of the 2020-2021 bowling season. The rule states all holes in a bowling ball must be used on every delivery; any hole not used is considered a balance hole, making the ball illegal.
Bowlers who do not use their thumb no longer can have a thumb hole, as it now is considered a balance hole. They also need to mark their ball to show where they place their palm on delivery.
Click here for an FAQ on balance holes and gripping holes.