Anecdotally every beginner violin student (and most players) I know use specifically Kun made shoulder rests. Instrument rental companies (where I'm from studen

Anecdotally every beginner violin student (and most players) I know use specifically Kun made shoulder rests. Instrument rental companies (where I'm from students rent instruments either through their school or a company, often run by a private teacher) generally include these with the cost of the instrument. The exceptions are generally not people using another brand but musicians not using the rest at all, many professionals will use just a cloth. Kun rests also rarely break, if ever, there aren't really any forces that would stress them. I wouldn't be surprised if they had started to be supplanted by cheap Chinese or other import brands, but I haven't seen it.