Part of the STI Wireless Chimes series that greets visitors with a pleasant chime and lets you know when the door opens or a person enters the detection zone. Mount the small transmitter and magnet to any door and plug the receiver into any 120VAC indoor electrical outlet. That's it. No wiring required. When a monitored door opens, the Entry Alert Chime sends a signal to the receiver announcing the entrance with one of ten selectable chimes.