I have played tennis using tretorn tennis balls, however i wouldnt recommend using it in competition. Its very heavy (too heavy) when hit hard and it can make loud sounds off the racquet. But i do believe it helps me sometimes out while im practicing. One good thing i like about these balls is that it enables you to hit with more spin and it lasts much longer than any other ball out there.For the first time i was able to hit hard consistently and the balls would "stay on the court" . I still hit sort of flat. I know people dont use these balls in real matches.