Stimove 2-bulb trackers Twidget (x3)

Set of 3 Twidgets, each filled with different-colored marbles (one blue, one green and one purple) and each with its own fill rate (90% - 60% - 30%). A single yellow marble is present in each Twidget, enabling visual tracking. The reward is the little noise made by the yellow ball as it passes from one bubble to the next.