Pressure competition Tennis Ball. The Club Ball is a lively, high-performance Ball that has good longevity. It is equipped with the new X D-Core technology. It is a revolutionary technology that reduces Ball deformation during play by 20%. This innovation allows the core to maintain its initial shape over a longer period of play. At the same time, the Ball maintains the same dynamic signature and therefore the same sensations. Play longer with the same gameplay. Ball intended for good level players. ITF and FFT approved.