Bellman Visit Push Button Transmitter

Bellman Visit Push Button Transmitter
Retail price: $79.95
Sale price: $69.95

When the Push Button Transmitter is pressed, a radio signal is sent to a Bellman Visit receivers. Attach the Push Button Transmitter outside your door to use as a doorbell or indoors to get someone's attention. For indoor use and outdoors in sheltered locations. Includes one PX28A alkaline battery and necklanyard. Two year warranty.

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.