an inflatable sport ball , such as a basketball , a football , a soccer ball , a volleyball or a playground ball , is provided with a self - contained inflation mechanism , or multiple self - contained inflation mechanisms , for inflating or adding pressure to the ball . the mechanism is a pump which is positioned and retained inside of the ball and which is operable from outside of the ball to pump ambient air into the ball . the pump is a dual action pump allowing air to be added to the ball on both a forward stroke and a reverse stroke .