The product was defective. On the first day, I used it for 26 minutes and it still had battery. On the second day, even though I charged it for a long time, it only worked for a few seconds and on the third day, when I tried to charge it, it started smoking and smelling burnt!!! It also made a terrible noise. Of course, I asked for a return and replacement. We will see what the replacement will do and I will come back. As for the method, from my little experience, it really does the job. Whether it's vibration or shocks, the muscles really relax and you become a different person. The most important thing is that endorphins are obviously released and you feel a general well-being and improved mood. You don't need an expensive machine, they all do the same job, as long as they work. The replacement arrived here a few days ago. So far, it's doing its job perfectly, it's worth the money and more. I decided to initially get a cheap one to check the method and I have already bought a more expensive one. The only drawback is that it makes a lot of noise, hence the 4 stars. As for durability, time will tell.