Not sure, but....
I'm not sure how to interpret this, but the following is from the USGA website:
Appendix II, 1a goes on to state that:
All parts must be fixed so that the club is one unit, and it must have no external attachments. Exceptions may be made for attachments that do not affect the performance of the club.
In explaining this part of the Rule, it is easier to divide it into the following four sections:
iii) All Parts Must Be Fixed
This is interpreted to mean that no part of the golf club should be designed to move, nor should it be promoted as doing so. Therefore, if any part of a club were to incorporate moving powder, pellets, liquid, vibrating wires, rollers, tuning forks, or any number of other features which could be considered a “moving part,” it would be in breach of this Rule. Additionally, this provision is interpreted to mean that with some exceptions, when assembled, all parts are bonded such that they require heating to loosen. Of course, this does not apply to clubs with permitted adjustable features.