To use the pocket electricity generator, you must first wind-up its starter ring. This causes the ring to transmit an impulse to the rotor. In order to keep the rotor spinning you will have to rotate the device in your hand with your wrist. The magnetic rotor in HandEnergy transmits a mechanical power with an average speed of 5,000 RPM to create an electric current. The built-in batteries are then charged this way. As soon as it has charged up, you can simply plug in a USB and pass the energy to the handheld device you are hoping to add some battery life to.