Saluc now called the wpa Rule:
Copy from http://www.wpa-pool.com/download/spec.pdf
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The cue tip may not be of a material that can scratch or damage the addressed ball. The
cue tip on any stick must be composed of a piece of specially processed leather or other
fibrous or pliable material that extends the natural line of the shaft end of the cue and
contacts the cue ball when the shot is executed..
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Thats a vicious circle. Going on and on.
Copy from http://www.wpa-pool.com/download/spec.pdf
-----
The cue tip may not be of a material that can scratch or damage the addressed ball. The
cue tip on any stick must be composed of a piece of specially processed leather or other
fibrous or pliable material that extends the natural line of the shaft end of the cue and
contacts the cue ball when the shot is executed..
------------
Thats a vicious circle. Going on and on.