a perfect security device. Don't open your door until you see who's out there. I was selling these units for $350. This is my last one. letting it go for $100 firm. The way it works . . . a small doorbell is placed at the outside entrance. When the bell is pushed, it activated the camera on the phone and you can see and speak to the visitor, but the visitor cannot see you. This unit is brand new in the box. 773-3038 to pick it up.