Today, anyone can buy devices that look like USB flash drives but are really automatic keyboards. They can then load their malicious payload onto the device, and leave it in your driveway or next to your desk at work. When you connect the device to a computer it acts as a keyboard, sending keystrokes just as if the attacker is typing on your keyboard.
Penteract Disguised-Keyboard Detector 2™ protects your computer by locking the screen when a keyboard is connected. If you connected a real keyboard - go ahead and type in your password. If not - the covert malicious device will not be able to run commands on your computer any more than could a person sitting in front of your locked screen.