DK tennis ball machine uses counter rotating wheels to propel the balls. It is the most effective method of ball propulsion allowing the machine to remain silent and effectively produce topspin and slice. The wheels are black to help disguise their location inside the machine, helping to make each shot almost unpredictable. To make your training more effective, unpredictability of shot is what you
These machines have “extreme grip” throwing wheels which can create very high levels of topspin & slice. When set at the maximum level, the difficulty of the spin is so high that if you can master it, you will have no trouble dealing with your opponent’s in real match play. Of course you can always set the spin to much easier levels for more realistic practice.