Automatic Power Failure Alarm, 120db Power Cut Alarm, LED Indicator Failure Outage Alarm, Smart Warning SirenPower by 9V Battery (NOT Included),Plug 175~265V

The product listing indicates "Plug 175~265V" so I was concerned it would not work with the standard US 110v-120v outlet even though it has standard a US blade configuration, but it worked properly and I am pleased with it.No instruction sheet is included and the instructions on the outside of the box are only in Chinese.Fortunately, use is reasonably intuitive. There is a sliding battery cover at the bottom of the unit. Though it took me a few moments, after removing the cover, I did eventually find a small + and - molded into the plastic to indicate the proper orientation of the required, but not included, 9v battery. Interestingly, the On and Off markings for the switch to turn the unit on and off on the side of the unit are in English.After pugging the unit into an outlet and turning it on, when power to the outlet was disrupted, the alarm sounded and a red LED on the front of the unit flashed. The alarm is loud and pulsating so it definitely got my attention. When power was restored, the sound and flashing stopped as expected.There is a place at the top of the unit through which a thin string can be looped to allow the unit to be hung, but there is no indentation in the back to allow the unit to be hooked over a nail/screw placed into the wall, nor are there holes to allow the unit to be screwed into a wall.Note that unlike more expensive units, there is no pass-through into which to plug a device, so you lose the use of one outlet.

Bought as a gift for a friend whose freezer kept going out. How embarrassing that it did not work.

Yes, this alarm works. Extremely loud. 120db sounds about right. It may wake the dead, but may also keep them away. Good buy if you need one of these.

This alarm foes exactly what it should do. And it's LOUD!

Right out of the box completely dead. Plug it in, turn the on switch and the light doesn't come on. So I tried using it as it is supposed to be used on another power source, and cut the power off to where this was plugged in and again, zero-nothing-nada. Useless junk. Back it went. Find another brand to buy if you want one.