what does DOT mean? and is there any difference between Off-Road and On-Road lights?
Way back in the day, the US Department of Transportation (DOT) set up a bunch of rules for headlights. They wanted to make sure you can see the road at night, and that you're not blinding other drivers while you're doing it.
The process to get DOT approval is long and expensive and they won't even look at some types - say older technology for cars that aren't made any more and only appeal to a small core of enthusiasts.
The headlights work the same way they do in Europe, but they don't have the official DOT seal of approval, so they're not considered legal in the US for vehicles that travel on the roads. A vehicle that only goes off-road is fair game, and you can put pretty much anything you want on it. If you aren't in the US, or if your state doesn't do regular inspections, there shouldn't be a problem unless you run across a bored cop with too much time on his hands, a knowledge of MB lighting and DOT regulations, and an attitude.