What you're looking at here is actually five tools in one including a box cutter, a bottle opener, a metric and imperial ruler, a multi-sized wrench, and a flat-head screwdriver. But that's just its official uses. With enough imagination this can come in handy for countless other uses, even gaining access to your home if your actual key's gone MIA.
And it's just $5. Break that down and you're paying just a buck for every tool this little wonder emulates. You can't even buy a decent screwdriver for that much, and especially not one that will sit as comfortably in your pocket as this one. More here.