I can't see the driveway entrance from my office so whenever there is a delivery I don't usually know about it until it's already too late.
This easy to install device has fixed that problem. It is wireless, has a sender and receiver unit which can be sited quite some distance apart, mine are about 20 meters away.
Whenever someone or something passes though the beam the chime sounds in the house alerting me.
It's refreshingly simple and it works, It even have a volume setting.