Bellman Visit Door Transmitter BE1411The Bellman & Symfon Visit Door Transmitter is a part of the Bellman Visit notification system, and when paired with one or more Visit receivers it will notify you when guests are at the door. Features May be used to "listen" for an existing doorbell door chime (through a built in microphone), or hard wired directly to your doorbell Includes velcro for easy wall mounting Multiple ports can detect doorbells or intercoms Battery lasts up to 10 years