The Brinno KNS100 Knocking Sensor detects any vibration from your door, and sends a signal to the PHV1330 PeepHole Viewer, which in turn captures images of the visitor. This is a handy device that will let you know who came to your home while you were away.
Used as an extension accessory for the Brinno PHV1330 Digital PeepHole Viewer
Fits into a slot on the back of the Digital PeepHole Viewer
Senses the vibration produced from knocking and captures an image of anyone at your door
Provides added security by allowing the Digital PeepHole Viewer to record photos of who's at your door even when you're not home