So. From the first time, the springs inside start to detach and your body comes into contact with the hard plastic, and as you go to exercise, it hurts. Now, if you like to do the exercise quickly (like I do), then this does not develop enough speed to intensify the exercise. I had gotten another one which, although it was better in terms of exercise, eventually broke and I was very disappointed. This is quite boring for my taste. Very poor quality materials and you can see it after a few days of use. Clearly. In the end, such products should cost maybe 10 bucks at most for their durability, in my humble opinion!