What is a Powerball ball?
When you look at the powerball, it looks like a fun toy, but in fact it's a gadget, whats designed in 1973 to allow to train astronauts in space. In 1994 it came this product to Europe.
You can train your arm, leg and shoulder muscles with exercise. By moving the powerball you train your muscles. Which muscles you train depends on the way you use the powerball. This makes it ideally suited to tackle RSI and CTS.
Inside the powerball there is a rotor (gyro). How faster it is spinning how heavier you're training.