These sort of devices should come with (or at least offer the option of) a special band that attaches to the device and leaves some amount of room at both ends with two 20mm connectors so one can attach a formal watch to the area 180° around the wrist. They'd probably be even more accurate if worn this way (with the sensors placed on top of the inner wrist where hair/tan skin can't interfere with signal processing) and customers with a bunch of classic watches would love for the ability to add smart features (especially ECG) to their mechanical watches.

I think Sony made a device like this years ago. If I remember correctly, the device replaced the clasp of a watch band with 20mm lugs with a sensor array and a battery. I don't think it sold very well though, as it had relatively poor battery life for a device without a screen.

Bei manchem Billigkopfhörer entsteht ein Knacken der mechanischen Bauteile, wenn den Kopf oder Hörer am Kopf leicht bewegt. Ist so etwas bei dem teuren Kopfhörer auch nach jahrelanger Nutzung ausgeschlossen?