We have provided one Bluetooth 4.0 low energy USB adapter in the box with each Myo armband. To ensure compatibility across multiple PC manufacturers (there are many different Bluetooth adapters and implementations), the Myo armband requires the included Bluetooth adapter. We are working on adding support for built-in Bluetooth 4.0 LE adapters in the future.
The USB Bluetooth adapter does not have a Host Controller Interface mode so you will not be able to connect other Bluetooth enabled devices to it. It currently only connects to the Myo armband.
Most computers will automatically detect the adapter and install the necessary drivers.
If the necessary drivers do not install automatically, please check out this article for more information.