I also miss adjustment, a simple wire with rubber coating could be adapted to jedwelche physiognomy. Here that is not the case, even without the cable problem I could not use this headset.
A normal 20-Euro-Bluetooth headset fits with me easily, and slips because nothing wobbles.
Too bad, I was hoping a (still) be able to achieve better call quality without latency with this headset. That might be possible if the volume of the other party would not vary constantly and significantly by the constant shifting.
Unfortunately, this is the second Sennheiser headset that I have to return. The other Neckband was also unusable for me. Probably remains only the design of headphones or even my existing Bluetooth headset.