A two-in-one hand exerciser. On top, the marble can roll gently and in a controlled manner. Inside the ring is another track where speed must be built up to make the marble rotate horizontally in circles with centrifugal force. The slightly raised edge on one side helps with starting up.
The top lane requires softness, good power control and insight. The inside lane requires coordination, speed control and good judgement.
In both jobs the movement can come from the wrist, but also from the shoulder. Try the difference, they are two completely different possibilities.