The basic ball
baseballs are 9 inches in circumference. Some leagues for
under-10 year old players may use a slightly larger ball.
Softballs typically are 12 inches in circumference, while some women's
and youth leagues use an 11 inch ball.
Balls are manufactured out
of leather or synthetic leather. Leather is used in the Major
Leagues and other upper-level leagues. Synthetic leather is used
primarily for balls in the Little League age group and younger
also safety balls for younger players.
"Safety balls" are engineered to play like a real ball without the sting
of a hard ball. They are known as "Reduced Injury Factor" or RIF balls,
they roll and bounce like their harder balls, but don't hurt as much if
the player gets hit.