The SS4610/RC4610 Motion Activated Chime by Carlon is an inexpensive, simple to install wireless entrance alert. It will monitor an entrance and send a wireless signal up to 150 ft away. This device can be expanded to cover multiple entrances as well. You also have the option to select different tunes to tell which entrance is sending the alert. The best part about this device is it will install in minutes with absolutely no wiring needed!