They are terrible headphones with thousands of failures.

To begin with, the bluetooth link is very bad. It takes a long time to connect and many times it fails. And do not even think about wearing the headphones when you make the connection, because at the moment it connects you will hear the phrase “YOUR DEVICE IS CONNECTED” in a very loud volume that destroys your ear. So also when you turn it on and turn it off, the same thing happens.
Another point that seems totally disastrous is the fact that anyone can connect to your headphones, so you can be in a library, on a subway or in any public place, and people can detect your bluetooth connection and connect to it, even though you already have it connected to a device (to your notebook or your cell phone). And the worst part is that when you connect to another device, it repeats the phrase “YOUR DEVICE IS CONNECTED” with an atrocious volume.

So also when the battery is low you start to hear an extremely unpleasant sound at a very high volume, something like a horns.
I set the volume to the minimum, nevertheless it makes heads explode, I do not even want to imagine what it would be like at a medium or high volume level.

The sound is good but not so much. However, when you are not listening to any sound or music you hear a very unpleasant cutting sound to supposedly save battery. I sincerely consider it lousy, because I usually use them to watch videos or similar, and every time I change the video that terrible cutting sound is heard.

They are the worst headphones I have bought. I do not understand how people can make such bad headphones, I feel really cheated!
I can not reach words to criticize this shit of headphones, if they could be called headphones. I feel very disappointed and my score is 0/10. I will not even give it a point, because the mistakes they have committed are unforgivable.