This is a great tennis ball basketball dribbling drill to help improve your handles and your hand eye coordination. The reason why is because you are forcing yourself to do two things at the the same time. You must do the side windshield wiper with the basketball with one hand, and then at the same time use the other hand to toss and catch the tennis ball against the wall. This is also great basketball drill for players that are constantly looking down at the basketball when they dribble. The tennis ball will force them to keep their eyes up.