I wasn't quite sure what this was or exactly what it did when I saw it. However I ordered it after reading a few reviews. Stupid thing to do? Absolutly NOT! Powerballs are brilliant, but hard work. It looks like a plastic ball encased by another plastic ball. But set it going and its more of a work-out than using free weights. Once you set it going give it five minutes, if that!, and you will feel it working. It works out your fingers, wrist, forearm and upper arm. For somehing that looks so simple it is absolutly amazing.
After I brought one I showed a few mates, every person I showed now has one. Most reviews seem a bit extreme, but they really are as good as these people say. Worth the next-to-nothing price they are.
Buy one and you won't regret it!