This Doorbell Notification package from Bellman & Symfon is part of the Visit Smart Home System that helps you to keep tabs on your home. This package includes a Door Transmitter, Flash Receiver, and Bed Shaker. Those alerting devices in this package are already paired as a system and ready to use out of the box. Just place the Door Transmitter close to your existing door chime and when someone rings your doorbell, you will be alerted with colored LEDs and bright flashing lights from the Flash Receiver and strong vibrations from the Bed Shaker which will wake up even the heavy sleepers. The backup batteries on the Flash Receiver will keep the device fully functional even during power outages. Simply place the Flash Receiver in your living room, bedroom, or kitchen, and you will notice the bright flashing lights even from rooms away. This package is a great signaling system to help people with hearing loss, hard of hearing, and deaf not to miss any visitors.