OK, but poor ergonomics

Bought for daily commuting in public transport, this headset is correct: the sound is good, the microphone is quite good, it PAIR easily and with multiple devices.
It's not a super helmet sonically, let's be clear, but frankly, there is much worse!
At first I had as pointed comment a little hissing sound in the right ear, but he disappeared.

No, where the bat really hurts is the ergonomics plan:
- The helmet is not adjustable width
- Once unfolded, the arch is really hard
- The earloop is lousy, with a recess just behind the ears

Clearly, with a coat, or a seat, abuts the hoop and move the headphones. If nothing interferes, he quickly badly behind the ears. I have a rather large head, I thought it was coming from there, I did try my wife: same verdict.

Suggestions:
- Use a more flexible material for the headband.
- Provide on-ear softer material / soft / soft.