USG is an attachment that allows users to connect USB flash drives and other USB devices to their computer without any of the risks. USG, created by New Zealander Robert Fisk, works as an intermediary between the computer and the USB device (flash drive, USB keyboard, USB mouse) and behaves like a firewall, inspecting the data that passes through it. The only downside to USG (by design) is that it doesn’t distinguish between good data and bad data. The recently released USG v1.0 only supports a data transfer speed of up to 1 MB/s.
Source: https://www.bleepingcomputer.com/news/hardware/this-device-works-as-a-firewall-for-your-usb-ports/