5.1 1 The ball dynamic stiffness is a measure of a ball’s hardness. Its measurement is conducted to represent bat-ball impact forces. It is normalized by the ball weight and speed to minimize the influence of manufacturing and test variations from the measure.

5.2 The cylindrical coefficient of restitution is a ball property of relative velocity change caused by impact with a cylindrical surface.

5.3 This test method compares the performance of baseballs and softballs after impact with a cylindrical test surface.

5.4 Sports associations can use DS and CCOR measurements in specifications for official baseballs and softballs.

1.1 This procedure describes a method of measuring the dynamic stiffness (DS) and cylindrical coefficient of restitution (CCOR) of baseballs and softballs providing similar impact forces and ball deformation as are observed in a bat-ball collision.

1.2 This procedure is for a ball that is intended for the game of baseball or softball.

1.3 The test method is based on ball speed measurements before and after impact with a cylindrical test surface and the impact force between the ball and impacted surface.

1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.