I love the a korfker rest but wanted it a little higher and nearer my neck. These parts allow a number of adjustments to the position of the rest. It is however difficult to adjust and needs a lot of time and trials to get it to work. In addition it does not come with instructions, something I found surprising given the expense. An email to Pirastro got me a link to some instructional videos which were helpful but some literature or even a note of the video link would be appreciated.
In summary, expensive but does add to the versatility of he most comfortable shoulder rest I have used.
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