Kindle Fire HD charges with a standard USB voltage (around 5 Volts). It's the charger (transformer) that needs to handle 100 and/or 220 Volts. Most these days do. This information should be written or stamped onto the charger.
Advice of illiterates is best not taken. I think I'll look for something else, thanks.
your = you're
should HAVE been made
searching for days (not day's)
THEIR (not there) widget wouldn't work
lots of gibberish in between
free one is good, TOO (not "to")
:-!