Retractable Doorknobs Provide Turtle-like Security

This design for a retractable doorknob provides extra security for your door by recessing into the doorframe when you leave the house, thereby preventing thieves from picking your lock (there are none). But if you want to get in, you use (we're assuming) the little slot below the knob to extend the knob out so you can… » 7/30/07 6:00pm 7/30/07 6:00pm