A regulation play baseball cut in half. A baseball must be 9 to 9 1/4 inches in circumference and weigh 5 to 5 1/4 ounces. The center of the baseball is cork. The cork ball is covered with rubber. Cotton and wool yarn are wound around the cork and rubber center. The covering of the ball is cowhide. Two pieces are sewn together with exactly 108 stitches.