Holes:
The following limitations shall govern the drilling of
holes in the ball:
1. Holes or indentations, not to exceed five (5), for
gripping purposes. The player is not required to use
all the holes in any specific delivery, but they must
be able to demonstrate that each hole can reasonably
be used for gripping purposes. Any hole that
cannot be reasonably shown to be used with a single
hand would be classified as a balance hole.
2. One hole for balance purposes not to exceed 1-1/4
inch diameter. (Including the surface opening).
3. No more than one vent hole to each finger and/or
thumb hole not to exceed 1/4 inch in diameter (including
the surface opening). This hole may not exceed
1-1/4 inch at any point through the depth of
the hole.
4. One mill hole for inspection purposes not to exceed
5/8 inch in diameter and 1/8 inch in depth.
Balance:
The following tolerances shall be permissible in the balance
of a bowling ball used in certified competition:
1. 10.01 pounds or more:
a. Not more than 3 ounces difference between top
half of the ball (finger hole side) and the bottom
half (side opposite the finger holes).
b. Not more than 1 ounce difference between the
sides to the right and left of the finger holes or
between the sides in front and back of the finger
holes.
c. Aball drilled without a thumb hole may not have
more than 1 ounce difference between any two
halves of the ball.
d. A ball drilled without any finger holes or indentations,
may not have more than 1 ounce difference
between any two halves of the ball.
e. A ball used without any hole or indentations
may not have more than 1 ounce difference between
any two halves of the ball.
f. Any ball used with a two-handed delivery with
or without holes or indentations may not have
more than 1 ounce difference between any
two halves of the ball.
2. For a ball weighing 10.0 pounds to 8.0 pounds:
a. Not more than 2 ounces difference between top
half of the ball (finger hole side) and the bottom
half (side opposite the finger holes).
b. Not more than 3/4 ounce difference between the
sides to the right and left of the finger holes or
between the sides in front and back of the finger
holes.
c. A ball drilled without a thumb hole may not
have more than 3/4 ounce difference between
any two halves of the ball.
d. A ball drilled without any finger holes or indentations,
may not have more than 3/4 ounce difference
between any two halves of the ball.
e. A ball used without any hole or indentations
may not have more than 3/4 ounce difference
between any two halves of the ball.
f. Any ball used with a two-handed delivery with
or without holes or indentations may not have
more than 3/4 ounce difference between any
two halves of the ball.
3. Less than 8.0 pounds:
a. Not more than 3/4 ounce difference between the
top half of the ball (finger hole side) and the bottom
half (side opposite the finger holes).
b. Not more than 3/4 ounce difference between the
sides to the right and left of the finger holes or
between the sides in front and back of the finger
holes.
c. A ball drilled without a thumb hole may not
have more than 3/4 ounce difference between
any two halves of the ball.
d. A ball drilled without any finger holes or indentations,
may not have more than 3/4 ounce difference
between any two halves of the ball.
e. A ball used without any hole or indentations
may not have more than 3/4 ounce difference
between any two halves of the ball.
f. Any ball used with a two-handed delivery with
or without holes or indentations may not have
more than 3/4 ounce difference between any
two halves of the ball.

The player is not required to use
all the holes in any specific delivery, but they must
be able to demonstrate that each hole can reasonably
be used for gripping purposes.