The raspberry pi has no switch, so it's trouble to control its power supply except drawing the usb. That's inconvenient especially in the process of preliminary debugging. So buy a power supply cable with ON/OFF switch is necessary. Not only for raspberry but also your mobile phone and other micro USB devices. It benefits to keeping on your device-battery's working life.
The switch is designed to come close to your Pi so that you have have to reach out far to turn on and off the power.
Use it for charging / powering the Pi. Not for data transfer use. Support up to 2000ma power.
