With Subtle revisions in design, choosed by the world¡¯s famous tennies player Roger Federer, Wilson K Six One Tour 90 Tennis Racquet offers every player with incomparable stability, comfort, feel and control. Wilson [K] Factor combines the next generation in Nanotechnology? and unique frame innovations that have resulted in the ultimate line of control racquets for all players.Compared with Wilson ProStaff Original 6.0 85, this rancquet has a shorter pallet with more of the graphite shaft exposed below the yoke.Another subtle update to the KSix-One Tour 90 is the string spacing in the sweetspot of the racquet. With the new KSix-One Tour 90 we now get four cross strings, just like Federer.