The USG is a small, portable hardware USB firewall that isolates a potentially harmful device from your computer. It's designed to prevent malicious USB sticks and devices laden with malware from infecting your computer...
The problem is that most computers automatically trust every USB device that's plugged in, which means malicious code can run without warning.
It's not just computers: Cars, cash registers, and some ATMs also come with USB ports (desk phones and printcenters, too), all of which can be vulnerable to cyberattacks from a single USB stick.
While the USG will protect against low-level USB attacks, it won't protect against malware stored on the flash drive itself.
Fisk explained on his Github page, where the code is available, that the project is "particularly useful for individuals and organizations that face advanced threats including corporate espionage or state sponsored attacks." more