1) The world most prominent artificial power purely mechanical device, no battery and no power, no electromagnetic radiation, natural and induced magnetic field generated by the magnetic analog of celestial bodies, and by the rotation of the wrist produce a strong driving force, through human control, any mediation motion rhythm and intensity, the faster the rotation kinetic energy generated stronger.
2) Wrist ball is a portable trainning device, it does well in arm trainning to keep muscle stronger . There's no battery or electricity inside the device, It is application by centrifugal force & inertia like a gyroscope. Use the rope twine and taut the ball, and take the rope into the above hole, quickly pull the rope down, then the rotor rotated at high speed.