Every circuit starts with power. It provides the electricity that makes your Bits spin, buzz, blink, and shine. This power Bit get's it's energy from a 9 volt battery.Use the small power switch on the side of the Bit to turn your circuit on and off. The power Bit converts the 9 volts of electricity in the battery to the 5 volts that littleBits circuits run on. The power Bit also sends a signal through your circuit. Controlling this signal with inputs is how you control your circuit. NOTE: Does not include battery or cable. This power Bit has a detachable battery cable