The Tecnifibre Tennis Club 4-Ball Tube is a lively, high-performance ball that has good durability.It has been designed with the new X D-Core technology whichreduces ball deformation during play by 20%. This innovationlets the core of the ballretain its initial shape over a longer period of play. It also maintains the same dynamic signature and therefore the same sensations.The Club balls areintended for good level players.ITF and FFT approved.