http://www.usga.org/rules/rules-and-decisions.html#!rule-14324 false Appendix III - The Ball Appendix III - The Ball 1. General The ball must not be substantially different from the traditional and customary form and make. The material and construction of the ball must not be contrary to the purpose and intent of the Rules. 2. Weight The weight of the ball must not be greater than 1.620 ounces avoirdupois (45.93 g). 3. Size The diameter of the ball must not be less than 1.680 inches (42.67 mm). 4. Spherical Symmetry The ball must not be designed, manufactured or intentionally modified to have properties which differ from those of a spherically symmetrical ball. 5. Initial Velocity The initial velocity of the ball must not exceed the limit specified under the conditions set forth in the Initial Velocity Standard for golf balls on file with the USGA. 6. Overall Distance Standard The combined carry and roll of the ball, when tested on apparatus approved by the USGA, must not exceed the distance specified under the conditions set forth in the Overall Distance Standard for golf balls on file with the USGA.