A regulation baseball must weigh between 5 and 5-1/4 ounces, according to current Major League Baseball rules.

In addition, the ball must be spherical in shape and composed of a small core of cork or rubber with yarn wound around it, all covered with two strips of white cowhide or horsehide.

The two pieces of a baseball cover are sewn together with 108 double stitches.

An umpire can remove a ball from play if it becomes misshapen or discolored, or if it comes apart during play.