However, some improvements would be relatively easy doable:
* The Ohrpölsterchen look cheap and not very durable. Perhaps it would be better, no mitzugeben and for making the ear piece a little more comfortable (eg roughen the surface).
* The brackets are very thin and can be adapted to the ear (bent). However, they bend again and fit loosely in the ear. Nevertheless, they remain curved and "hang" (also while running) at least at the ear.
* The cables are comfortably slim, but not flexible ("tissue sheath") and roll up easily. The cable length is 1.2 m just right (of course depends on the users circumstances from).
* Some headphones have a sliding sleeve over the two cables that holds them together when moving up to the handset parts and helps organize messy cables. That would be very practical here.
* The volume slider is for those who need it, very convenient. Unfortunately, the operation is relatively cumbersome (small, hard to pin down, too light and therefore difficult to adjust).
* What is true of the Ohrpölsterchen and the volume knob, also fit the supplied bag. "Nice to have", but more fundamental product improvements would make more sense instead.
* Last nor something individual: The sound is in my opinion OK, but could (if only because Sennheiser is on it) be much better, ie more bass and treble and in general a little louder.