Gegong Automatic Power Outage Alarm, 120db Power Off Alarm, LED Indicator Failure Alarm, Smart Warning with SirenPower 9V Battery(Not Included), Plug 175~265V

Holy cow, this sucker is loud I should have no issue hearing it when it goes off in the basement.

Alarm didn't work. The battery had to beheld down bybhand to get it ro work.

Excelente. De mucha utilidad.

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

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.