It is the weigh-controllable dumbbell. The revolution of the ball inside of the dumbbell leads this design possible. If the user wants the different dumbbell weigh, only thing he have to do is just change the revolution speed.
Many people cannot work out because of the lack of time. Also, there are not many places people exercise. This slim dumbbell is a good solution for these busy people. Because of the good portability, it will give healthiness to the busy people.