only example, there are many different one's out there and seemed to be safer and better than a inverter, I have had bad Luck with inverters of cigarette lighters. They all ways seem to heat up and cause problems. Those problems go away with 1000w and above, but who wants to lug around a 10 pound inverter and wire directly to the battery every time. Nightmare.
I need everything to be portable where external battery would be the best bet.