What is this little beeping thing?

[Scott Forman]

Mounted below the refrigerator near the floor in my FC kitchen is some
sort of detector/alarm device. It has a small red LED light that is
always on, and a 'test' button that emits a high-pitched alarm when
pushed. What is this an alarm for?

Every once in a while, it will beep once. Usually the beep seems to
happen when I am operating on battery power and the water pump is
activated. It doesn't do it every time. I wondered if it might be
some sort of low battery voltage alarm, but it will sometimes let out
the beep even when the batteries are fully charged. It has never gone
off any other way.

What is this thing?

Scott Forman
82 FC35RB
Memphis