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 which reduces ball deformation during play by 20%. This innovation lets the core of the ball retain its initial shape over a longer period of play. It also maintains the same dynamic signature and therefore the same sensations. The Club balls are intended for good level players. ITF and FFT approved.