FuzeA.bin is the firmware for the Fuze. Bin is for binary, written in computer language. That’s why you get the security warning–because it’s a .bin file.
But you are not going to run it on your computer (where it would probably just be ignored).
You just drag FuzeA.bin onto the driveletter for the Sansa Fuze, disconnect, and the firmware installs. Your computer has Windows (or Mac or Linux or whatever). The Fuze has FuzeA.
