Ordered this after I returned Magic Closer which did not work. I don't mind giving five stars but the product design was not taken into consideration of attaching to different shapes of garage doors. I started Mahler's Resurrection when I started installing the door sensor, expecting it would have been done 4 minute 23 seconds. But when I came back to inside after I finished attaching the sensor to the door, the Resurrection was on the Finale. You know it is the long piece of symphony. I had to improvise back panel to attach the sensor. I prefer the concept of Magic Closer to this, but I lost confidence for that after the first unit was defect.

The instructions were written by someone with a good comand of the English language but no mention is made of the type of battery used (a CR2032) or how long the battery should last. That oversight may be intentional as it is impossible to open the case (to replace the battery) without damaging the sides of the case. I had to file down parts of the case to make it easier to open.

These are pretty handy motion detectors. I got one sensor w/ receiver years ago (back then they didn't offer any of the other sensors) and it's worked great. Recently added a second sensor, and I like having the additional coverage/flexibility. The receiver has four zones (different audio alarm for each zone) and each zone can receive signals from four separate sensors (for a total of 16 sensors covering four zones). I had just the one covering my driveway (also lets me know when the mail arrives :) ). The 9v battery last about a year for me. The range is good, both my sensors are on the opposite side of the house (and outside) from the receiver. The motion detector also flashes a red LED when it's activated, so anyone setting it off knows they have been caught. Two different sensitivity levels. Occasional but rare "false" alarms (I've had birds set mine off). I've been happy with mine for years now. Nice expandable system.

I use these for security at apt. as soon as someone is on my stairwell i have a 15 second headsup that someone is out there. It can really differentiate between a small animal and human. Before bed i set the alarm to go off and it will wake you up if someone is on your property so you can take the appropriate action. This is just one extra security precaution. I like that you can put more then one on the unit.

Great Product! Purchased the WD-434RTL window/door alarm and the GM-434RTL garage door alarm about a month ago. It is just what I was looking for and works reliably so far. I turned off the audio alert and use it just for the visual LED lights to show if both garage doors are closed before I go to bed. Keeps me from having to make a trip outside to check at night on my detached garage. Last night I noticed the red LED for the big door was on so I picked up an extra garage door closer I keep inside and closed it from my desk. This is going to be so great when the snow flies this winter. Note: If you unplug the inside receiver it looses track of the door sensors until the doors have been cycled (opened and closed) one time then it reconnects by itself. This is only an issue if you unplug the receiver to move it. However, the range is hardly 800 feet. Mine struggles to maintain signal connection over 50 feet through two wood framed walls. I had to set the reciver next to a facing window and put the antenna up by the window glass. You might need to buy the Skylink Repeater RP-434 ($25) for longer distances. Love em!