I have had them for 1 week and I bought them for 18 euros after waiting for a month for them to arrive. The sound, kids, is so low and no matter how much you try to increase the volume (e.g. with equalizer apps, etc.), you will not have any result as they distort even with the little increase in loudness. I also tried them on my laptop in case it was the Android operating system's fault, but no chance, as they sound just as bad.

My daughter has the Xiaomi lite ones (purchased for 30 euros) and they sound twice as loud. To understand how low these play :(

Obviously, for battery life, nonexistent bass, etc., it is unnecessary to mention since they play so low that they are USELESS.

The worst purchase of 2020 by far.

Update 18/3/2021: I threw away the QCY ones. I spent 60 euros and bought the Creative Outlier Air V2 (which simply outperform the Xiaomi lite ones). Amazing sound for anyone interested in checking them out, and with a very long battery life (10 hours and 34 with the case). Extremely satisfied and highly recommend them.

It was a bit strange to learn at first because if you want to increase the volume, you touch your finger and drag it upwards on the headphones, and I understood this after a while!! But now that I know how they work, they are perfect and affordable!!!!!!

After two months of having them, I can express my opinion.
1. Long and satisfactory battery life, perhaps the only positive aspect.
2. The two earphones never play simultaneously.
3. They are very difficult to connect to the smartphone, and never both at the same time.
4. The touch function is unclear and often activates the radio application on its own, which is quite annoying.
5. Good fit in the ear.
6. It does not reduce background noises, and the person I am talking to often has communication issues. Also, many times, in closed spaces like my office, they say I sound very deep and distorted.
7. For the money I paid, which is 26 euros, they are not worth it because comparing them to much cheaper ones I have had, there is no significant difference

They arrived the next day, but after 5 days of having them, the sound suddenly stopped coming from the left earphone, while the touch function still works fine!