Autovolt here is more for surges than low voltage situations. ...
It's amazing just how much the voltage fluctuates in the poorer areas.
Voltage can drop so low that incandescent lamps dim to 50% intensity. Even that is ideal voltage to all electronics. Voltage variations (watching voltage go up and down) as describes are near zero. Voltage will always vary only by near zero amounts because too much variation is harmful to motorized appliances (ie refrigerator).
What happens when AC voltage drops to less than 50%? Electronics simply power off - without damage. What happens if AC voltage varies more than near zero? AC utility cuts off power so that larger variations do not damage what is at greater risk (ie refrigerator, air conditioner, washing machine).
How does that Autovolt stop what three miles of sky could not? It doesn't. It does not even claim protection from sruges that typically do damage. Again, it protects from surges already made irrelevant by existing protection inside electronics and refrigerators. Autovolt was recommended by a salesman who forgot to mention what is always necessary - specification numbers. Why did a salesmen forget to mention normal voltage for electronics is even when lights dim to 50% intensity? Did he fear losing an obscenely profitable sale?
Where are spec numbers that says an autovolt will stop 2000+ volts - a destructive surge? None exist. Where does it claim to absorb (make harmless) surges that are hundreds of thousands of joules? It doesn't. But somehow it is recommended to do what even the manufacturer does not claim it will do.
Voltage variations do not damage electronics but can threaten motorized appliances. Surges require something completely different that, to create confusion, is also called a surge protector.