The Internet is a scary place, and you need to be protected from all the goons and shady folks that call it home. Sure, you might think that you're safe when you're at the keyboard and therefore guarding the gates, but what about when you aren't at the computer? If you're one of the many people who leaves their computer on and connected to the Net at all times, you should have something in place to keep you protected.
The Databreaker hangs out between your computer and your modem, and when you aren't around it physically disconnects the two. Pretty tough for a baddie to gain access to your PC when it isn't online at all, eh? The $40 price tag is pretty reasonable, but to be fair there are software firewalls out there that will do the same thing for free. It all depends on whether or not you trust software to not get OMG hacked by cyberbaddies.