Here are the cue stick requirements for the WPA (and, therefore, also for the BCA):
17. Cue Sticks
Cue Sticks used at WPA competitions should comply with the following
during play at table:
Length of Cue: 40 inches [1.016 m] minimum / No Maximum
Weight of Cue: No minimum / 25 oz. [708.75 gm] maximum
Width of Tip: No minimum / 14mm maximum
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..
The ferrule of the cue stick, if of a metal material, may not be more than 1 inch [2.54 cm] in length.
The BCA Pool League has the same requirements in terms of length, width, and weight, but for break cues (not jump cues) they require that the cue tip be "leather with no non-leather materials added to the contacting surface."