For RC4MagicPC software to communicate wirelessly with remote RC4Magic devices, it needs an RC4 transceiver connected to the PC through a USB port on the computer. That transceiver is called a dongle. A dongle can be a dedicated device, like the RC4Magic XStick, or it can be any RC4Magic device in dongle mode and connected to the PC with an RC4 CodeLoader cable.
RC4 Glossary
dongle