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, Portable 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 audible sounds with adjustable volume up to 90dB from the Portable Receiver and strong vibrations from the Bed Shaker which will wake up even the heavy sleepers. The Portable Receiver is powered by batteries so you can easily bring it with you and place wherever you like. This package is a great signaling system to help people with hearing loss, hard of hearing, and deaf not to miss any visitors. So, are you looking for any doorbell for hard of hearing people? You can check this out.