The 16 inch softball has many uses. It was originally used as a "Chicago" ball or mush ball, because this is the size ball they play with. It is called mush because it turns to mush after you hit it so many times. Now a days we use them as training ball. It can be used as a grip enhancer to get more spin and movement on your pitch. Or, you can use them to help teach batters to push through the ball.
