When the Push Button Transmitter is pressed, a radio signal is sent to any Bellman Visit receiver. Attach the Push Button Transmitter outside your door to use as a doorbell, or indoors to get someone's attention (neck lanyard included). For indoor use and outdoors in sheltered locations. Includes one PX28A alkaline battery.

What else do I need to make this work?

In order to be notified, you will need to purchase a receiver that lets you know when the signaler or transmitter is activated.