This is a keystroke injection device (also called badusb). It is similar to a well-known USB rubber ducky made by hak5, but has much extended functionality, lower price and is also completely open source. It looks and feels like an ordinary USB flash drive, but acts as a keyboard that types in a preprogrammed payload. This payload can do anything from configuring a network to installing a reverse shell, since the device can basically do whatever an admin can with a terminal, but taking only a few seconds. This makes it a very powerful tool for automating sysadmin tasks or use in penetration testing.