In VoIP calls, the headset has served its purpose: I was very well understood and my interlocutor. MP3 listen to the headphones also very well received.
The cable is very long (about 3 feet) and includes a clip for Turning On / Off the headset and to adjust the earpiece volume, which can be fastenings, the shirt.
The only drawback: Some reviewers complain rightly that the mounting bracket in its size can not be adjusted. For smaller ears, it is therefore inappropriate. For me personally, it is an excellent fit and I have men's ears of average size.
Conclusion: Sennheiser satisfies its high quality claim. The price is therefore appropriate. Who needs a small, stable travel headset and not to small ears :), is In-Ear right the Sennheiser PC 121.