No high tech solution for you here, folks: no crazy encryption or a program that notifies you when your data has been tampered with. Instead, what we've got here is a good ol' fashioned combination lock, like the kind you use on your luggage or a locker. It's good enough to keep your friends from using your thumb drive, but secret agents should probably take a pass on this.
Why? All it's really doing is blocking access to your flash drive. Your data isn't protected in any way. An enterprising thief could simply rip the lock off — adapter and all — and then use special hardware to steal all your valuable secrets from the flash chip inside.
If you're interested, you can lock down one of these for $6.