Feedback from the keller-sports.com team:
348 grammes of weight (unstrung), 17 millimetres of profile and only 88 sqin head size - the most extreme frame on the market offers extreme qualities: extreme control, extremely brilliant touch, but also an extremely small sweetspot. If you hit the ball precisely with a really good and clean swing, then the ball takes off as if Pistol Pete himself hit the ball – but if you don’t hit the ball precisely…!
No problem for a 14-time Grand Slam winner. He can do whatever he wants with this racket and even meet every stamp on the other side of the net. However, the play level shouldn’t be much worse, otherwise playing the K Pro Staff becomes more work than pleasure.
Result: There are actually only two kinds of players for whom the K per Staff is the right racket: On the one hand purists with a great technique and perfect fitness, who maybe played the old Wilson Pro Staff Original before; on the other hand those Sampras fans, who want to play the racket of their idol at any rate, although they don’t really play good enough for this racket.
Manufacturer's description:
The [K]PRO STAFF® 88 was designed especially for Pete Sampras and features his signature on the frame. This racket provides solid stability and precision. With [K]arophite Black. For stronger and advanced level players.
Note : This racket is usually no more supplied with cover by manufacturers.