Softball is played by more people than any other team sport in the United States. Slow-pitch softball has specific rules about how the ball must be pitched to form an arc of between six to 12 feet from the ground. Softballs can be white or high visibility yellow, and most have a 12-inch circumference although minor leagues sometimes use 11-inch balls. A good slow-pitch softball should have high compression and high COR.
Compression and COR Ratings
Compression ratings indicate how hard the ball is. Good slow-pitch softballs should have a compression rating of 375 to 400. A rating of 375 means that 375 pounds of force is needed to squeeze the sides of the softball in one-quarter of an inch. High compression balls can be hit further. COR measures how bouncy the ball is, and the higher the rating, the farther it should fly on impact. Compression can change in high temperatures and in damp weather – particularly for leather balls – which can lower performance.