More microphones result in better sound quality and enable the device to filter out background noise.
Parrot Zik Sport: 8
16. cable length
A long cable ensures more freedom of movement.
Pioneer SE-A1000: 6m
17. has an on-ear form
This device comfortably rests on top of your outer ears. As it doesn't block out everything from the outside world, it's preferred in places like office environments and recommended for outdoor activities.
Harman Kardon CL
23% have it
18. diaphragm size
The diaphragm moves air back and forth to create sound. The bigger the diaphragm, the more bass it can produce.