The Tennis Tutor Plus Tennis Ball Machine - with Remote Control includes all the features of the standard Tennis Tutor, plus adds topspin and underspin capability. A simple dial controls the amount of topspin or underspin you desire. The machines includes an additional remote control which lets you start and stop ball delivery, and control the side-to-side position of the ball throws.. Tennis Tutor Plus is the only portable ball machine that displays the Elevation setting right on the control panel. A simple 10-segment display shows the elevation setting so you can set it to your favorite spot before firing any balls.