At first saw a gadget that is not really. The powerball really helps to test the muscles of the fingers up to the shoulder. Particularly true of the hand to the elbow, these muscles are not often accessed. I advise to practice alone, because the sound of friction of the ball is proportionally as weaving for others that de-stresses its user. Not to mention it may seem ridiculous waving his hands in a way that suggests a substitute for masturbation ^^