batteries last a long time on a single charge. the range is exceptional.

Batteries died after a month of use. Then batteries started draining as soon as replaced. No help from customer service even thought it is supposed to have a 24 month warranty.
Update: Hosmart contacted me and replaced the sensor. It is now working correctly. They have been very helpful and supportive and determined to make this right.

I chose this unit with two transmitters to monitor my road to my house. I set one transmitter about 400 feet away monitoring my driveway and the 2nd unit near my house so I get two different chimes telling me where the vehicle or person is.
Unit comes in pieces so be prepared to put it together. You don't need the instructions. It's pretty simple to do. Don't forget to plug in the power supply cable which comes disconnected so the battery won't be completely discharged when you receive it.
So plug in the power cable and before putting the cover on select the channel you want the transmitter to use. There is a small selector switch in it for channels 1 through 4. Each channel has it's own sound and has a light on the receiver showing which unit is alarming.

Now something very important about the channel selection is this: Channels 1 and 2 will have the transmitter sensor turn red when it senses motion. Channels 3 and 4 keep the transmitter light OFF when it senses motion.

So make sure if you don't want someone seeing the unit's red sensor light to select channel 3 or 4. I found that feature one of the best. I selected channels 3 and 4 so no one can see it when it senses motion.

There is also a switch to adjust the sensitivity or "range" of the sensor. I left both units at maximum range. Now what I discovered is quite interesting. The unit that is 400 feet away looks across my driveway towards another road that runs parallel with mine. The other road is about 150 feet away and is up a slight hill. When a vehicle passes by on that road the sensor picks up the motion and alerts. I really was a bit shocked about that so next time I charge it I will have to lower the range of that sensor.

Oh, and don't forget to charge the battery before you put it all together. There is a micro usb cable and power supply that powers the base receiver that is also used to charge the internal Li-OH battery. Make sure the battery plug inside the unit is plugged into the unit's board before trying to charge the battery. There is a small rubber plug/flap on the bottom of the unit where you plug in the battery charging micro usb cable. When the internal battery is charging the sensor light is blue. When charge is complete the sensor light is off.

Once done charging make sure you test the sensor with the base receiver and finally put it all together. There is a very small gasket on the unit so make sure it is in place before you screw down the cover or it will be offset and not seal. Don't over tighten the screws because it will cause that section of the cover to pop up (yes, I did this! Had to use hot glue to ensure it was sealed).

Mount it where you want it and that's pretty much it. The base unit is powered by either AA Batteries (4) or the included power supply. You can put batteries in it and plug it in to AC power so if AC power is off you still have the unit functioning. The volume on the base receiver can go quite high so adjust it to your liking.

All in all I am very happy with this system. I will update this after the Winter to write how it functioned in the sub zero cold here.

Hi,,,,I bought this driveway alarm because I wanted to be aware of who's coming and going. I found the alarm on a different website"¦.So I ordered it and it WORKS GREAT.. I emailed Hosmart to see if I could get Extra Monitors and they gave me the http/ address at Amazon for the second purchase. I ordered the 3 extra monitors tried to connect them and I lost ALL signals from the first purchase"¦.. so I emailed Hosmart for help and in less than 24 hrs they answered me back with an apology and a video how to solve the problem. Every thing works GREAT now! Thank you Hosmart for everything!! ( I just want to be clear I ordered "3" items"¦.NOT 1. Thanks again!!

You have to take the time to aim the sensor so that trees, bushes, etch won't wave in it's path, or it will give off false alarms. But once that's done it will work like a charm for years!