I have had several motion detector style driveway alarms, they all had a ridiculous number of false alarms. This thru-beam system has not had one false alarm. My property has a lot of slope from one side to the other so I had to devise a gimbal system to align the sensors. I have the sensors 100 feet apart (very easy to align) and the receiver in the house is 200 feet away. The system works great. The part I don't like is that there are 30 some alarm sounds that are music/songs, there is only one alarm sound.
the best item i found for what i want to do. i have a camera system, but not always looking at the cameras. now that i got an AUDIO sound everytime someone drives or walks through my driveway, i can look on the cameras not not miss any action.
the best thing about this item is that its solar and never has to be charged. i set it up, leave it alone, and still working today without any false alarms.