8 month review. This is an exceptional unit. Battery life on 2 AA batteries is unexpectedly long, even in winter. AA batteries are so much easier to deal with and source than other solutions that use CR123 batteries. Changing batteries is a breeze. I also like the activity light on the monitoring unit. The entire unit is built well and has survived well so far. I have absolutely no complaints about this unit.

Does exactly as described. Only issue is transmitter needs a good line of sight with receiver (no concrete or grade barriers)

I purchased this in the winter so currently have the sensor laying on top of the ground parallel to the driveway. It is under about 2 feet of snow and the distance from the driveway sensor to the receiver in the house is 150' and so far it has been working perfectly.This is replacing a motion detector and has been much superior in every aspect. No false alarms due to animals or weather conditions.I like the green "visitor" light that goes on after the alarm is activated and remains lit until you push the reset button on receiver in the house. This lets you know if someone has been down the driveway while you are not home or do not happen to hear the alarm.The cord could certainly be a little longer to allow the transmitter to be located further from the driveway sensor. Some posts have indicated they have added a USB cable to extend the length of the cord provided. This connection would of course be underground so proper precautions would have to be taken to ensure this connection is not affected by moisture. I cannot comment if this would have any negative impact on the overall performance of the driveway alarm.Overall, I have been very pleased with this so far and will bury the sensor and cable in the spring.

UPDATE: I recommend purchasers may want to stay away from this product unless they have tenacity and patience.My first Mighty Mule did not work for more than one week, so I immediately returned it for a new one.Amazon was great and sent a replacement one to me right away.I installed the second one and it also did not work, worse than the first actually. I lost interest in it and just started to investigate returning it to Mighty Mule today as I have tinkered with it over the last number of months to no avail.I have now been on hold for an hour trying to find out how to return it I have been shunted from dept to dept and no one seems to know what to do because I bought through Amazon.So a long story short... you may be on your own if you buy one of these. They work poorly...I have had two.They also seem to have poor product support and certainly no place to send an email inquiry....your only hope is to hang on the phone for quite possibly hours. Which I did.I was about to give up...and planned to write off my hundred dollar investment as a bad one.But...lo and behold, Finally I got through.The last gentleman I spoke to, Gregory, at Mighty Mule was very nice, helpful and I will be getting a replacement...hopefully third times a charm.NOPE: third one worked for about two years, stop working last spring….replaced batteries, dug it up and reinstalled….nothing fixed it. So disappointed.

Edit after 4.5 years.I am still very please with this unit. It's been running flawlessly for the last 4.5 years. Like I said earlier, I had to place the sensor unit at about 20 feet away from the main road. Because there is a lot of heavy traffic and sometime I got a false alarm because a heavily loaded semi truck went by. My driveway is about 100 feet long.Today after 4.5 years of continuous use, I had my first low battery warning. I use the brand name alkaline batteries. So the batteries last a very long time. I am sure my unit is still working fine in part because it is protected by an big PVC pipe (see pictures).--------------------------------Edit after 18 months.I am still very pleased with this unit. I am still running the same batteries since I installed it 18 months ago. The cold weather of winter does not seems to bother it at all. Even after been totally covered in snow it is still working fine. As you can see in my picture my apparatus is well protected with a big plastic pipe with very good venting. I believe this is important so humidity does not saturate the equipment.--------------------------------------------Great driveway alarm. Works great. No more false alarm. Before this one I had one of those wire less motion detector drive way alarm. About the third of the price of this one. But there were always false alarms. Animals (deer, cat, etc), branches moving in the wind and when the clouds keeps on hiding the sun intermittently, this was causing false alarms.Now with this one no more problems. Every time the alarm sound, there is a car in my driveway. I installed it about 30 feet from the road. I live on a very busy road, it is a road that lead to the US border, so there is always many cars and heavy trucks that go by. I happened to have a piece of 3 inches ABS tube with an elbow so I ran the device in the tube. I also happened to have a 4 inches PVC pipe. So I made a sleeve that slide perfectly over the ABS pipe. I just added a cover and put some holes (pointing downward) so there will be a good aeration and the rain will not enter. This way the access is very easy for maintenance and changing the batteries. I also painted it with some camouflage paint. Next summer, the grass will growth around the pipe and will help to hide it.The receptor does not sound very loud nor for very long. If you happen to sneeze while the alarm goes off, you will miss it. However there is a light that come ON and remain ON (until you reset it), to tell you the device have been triggered. Also it is possible to buy more receptors. I bought an extra one. Now I have one in my living / dinning room and another downstairs in the basement.Very handy, now I can be in my workshop in the basement without missing the delivery truck that brings me my Amazon parcels. Before that, I always hesitated to move far from my kitchen window when I expect a parcel. This is very liberating.

This sensor works exactly as described. It was easy to install following instructions - took about 1/2 hour.I placed the sensor adjacent to the drive paving about 50' up the drive from the street and placed the transmitter about 6' back from the drive near a lamp post for protection. I only buried the sensor and wire about 6" deep (hard ground) with no problem. I mounted the transmitter and one piece of the pipe on a piece of 1/4" plastic rod (electric fence post from Tractor Supply) which provides a solid support for the unit. I left the range setting at maximum and it seems to work fine for my location.I installed the receiver in the house about 200' from the transmitter. I had to test the receiver location and move it due to the construction materials in my house. My house is wrapped on the outside with heavy aluminum foil under the siding, which has caused me problems with wireless communication before. The best location for me was near windows in the direction of the transmitter.The receiver looks like a new model with some improvements from the product description and comments. The receiver has a volume control and the beeping sound is fairly loud when set at high. Actually I wouldn't want it any louder in our house. An additional change appears to be when the sensor sends an alarm, the receiver beeps 3 times at the volume set. The green (Visitor) light also turns on when the receiver gets a signal. You can reset it and turn off the green light if you like. I found it was handy to check the system - since we don't get much driveway traffic. Just reset it, leave for an errand and return. If the system is working, the green light will be on when you check the receiver. To clarify the alert actions, when the green light is off and an alarm sounds, the receiver will beep 3 times and the green light will come on. Every additional alert will beep 3 times and the green light will remain on. You can reset the green light manually at any time - or never.Have had the unit in service for 2 weeks so far without any problem. HAVE NEVER HAD A FALSE ALARM so far. This seems like a good solid well built unit and works exactly as we want.

This is an excellent product. It has mostly clear and accurate instructions.However, let me give a more detailed description of my experience. My drive is long and in the front of our house. All our windows are toward the back, so we could never tell when someone was coming without standing at a window waiting. So, the idea of a remote sensor was very appealing. I read the reviews for this product and it seemed as though concerns about range were that it would work well for my needs. However, I didn't want this 1' tall pipe with the transmitter standing in the middle of the yard. I was hoping to find a longer cord from the sensor to the transmitter so I could hide it by a tree at about 30'. I called customer support for the company to see if this was possible and found out that the cable that connects them is a simple computer USB cable...they suggested that I could add a longer extension cable to make it possible to hide the transmitter farther away from the drive (the cable is only about 10' long). So, I ordered the unit and bought some extra 6' long USB extension cables. When the unit came, I had a beautiful mid-winter 60 degree day and went out to dig my trench for the unit. Since I was burying the USB with junctions, I bagged the connections in plastic and used heavy tape to keep water out. When I completed the task, the unit worked GREAT! Total success. However, the next morning, it didn't work! Why? I never could really figure it out. The connections were all snug and dry, but the transmitter only worked intermittently. VERY frustrating. I called the company again. They said that perhaps the batteries were not able to handle the cold (it was no longer 60 degrees and was below freezing over night.) So, I went out and bought lithium batteries....no difference. Not only was it intermittent, but the frequency of success seemed to diminish.I read the manual again and found that it says "Do not splice the cable". I concluded that this meant I should not use the USB extension cables, even though the tech told me I could do this. So, I took out the extensions and put the pole the 10' from the driveway (ugly). But it worked for a day, then seemed to stop again...back to intermittent success. Back to tech support....they advised "resetting" the unit...taking the battery out for 30 seconds, then reinserting to let it recalibrate. I did this a number of times...every time I reinserted the battery, the alarm would go off inside. This told me that the transmission was good, but there was something hindering the signal from the sensor to the transmitter. I was ready to give up and called the tech support again. He told me that they had done all they could do to help me over the phone and they gave me a return authorization. He told me that I should be sure it didn't work because if they got it back and it worked for them, they would just send it back to me. (I was not really happy at this point...) However, I decided I would remove the item....as I brought it back into the house with the batteries still inserted, it set off the alarm whenever I walked past something with even a little metal in it. Hmmmm...this told me that it WAS properly sensing and transmitting and that perhaps my line of sight in my original location was not as good as I thought. I reburied the unit in a different location that is farther away from the house and not as obvious that the pole is sticking out of the ground...it actually has a superior line of sight to the house and ... VOILA! It works perfectly and every time now. I can't say for sure what fixed it other than the different location must transmit better.So, this was very frustrating to get it set up. 1) You need to be sure you can avoid splicing the USB and have a transmission spot 10' from the driveway. 2) You do need lithium batteries. 3) Be sure you have excellent line of sight from the transmitter to the receiver location in the house (it does not need to be through a window, however)...I may have had zebra grass blowing about 1/2 way between my original location...don't know. 4) The alarm is loud enough to be heard throughout the house. It will send a new signal with each car (after about 15 seconds between). 5) Once it is working, DON'T TOUCH IT! (I really don't know if it would affect it, but I am not taking any chances. My rating is 4* because of the trials and frustration getting it to work. As for the way it works, it is great and worthy of 5*. It works just as advertised finally and we can now await our visitors sitting in the back of the house without seeing the driveway. Good product.

I have taken several months before writing a review on this product, since I have had problems with other metal sensor driveway alarms in the past. In principle the technology is wonderful. We live in the country off a fairly busy County Road with our house screened by trees about 75 feet from the roadway. A motion detector does not work in this application because of animals, heavy trucks passing and various other "ghost" positives. We then tried two other makes of metal sensor alarm with mixed results. When they worked they were clearly the right technology for our application, but they ate batteries that were hard to replace, became infested with ants (the sensors were mounted on a tree) and they also gave off false positives from tree motion and especially when the batteries were low. In addition they seemed to be orphans from the start. We were on our own making them work. So, right technology, poor product - which is obviously why they are no longer on the market! Even with their flaws we found a driveway alarm to be very valuable to alert us to vehicles entering our driveway in our rural situation.After scouring the market for other metal sensing alarms for over a year, I finally took the plunge and tried the Mighty Mule FM231 with some skepticism. After 4 or 5 months of use, I can say it is exactly what were were looking for. It uses a sensor that is buried in the lawn beside the driveway (rather than pole or tree mounted). It takes AA batteries that are easily accessible and economical to replace ( I haven't yet had to replace them). It has a sensitivity control that can be adjusted to screen out everything but passing vehicles. My experience wasn't entirely problem free. The transformer unit used to power the house alarm which came in the kit was defective, but even this turned out to be a positive experience. I had no trouble contacting a knowledgeable technical support person at the Florida headquarters of Mighty Mule and he arranged for a replacement transformer to be couriered to me at the manufacturers expense with no fuss or hassle. That is comforting!I should caution other potential buyer that I cannot comment directly on the effective range of the wireless signal from the transmitter to the house since we have a short driveway and the transmitter is less than 20 feet from the receiver in the house, but I have moved the receiver around a bit within the house and there seems to be no problem with fading signals through the triple brick walls. I would have reasonable confidence that it would work over substantially greater distances. So my conclusion is right technology, right product. I hope this helps.