They don't really say. They would if they are up themselves in marketing etc, but otherwise you will be fine. If you read my post again (as I have edited it just then), you will see that most, if not all, are AC anyways. you are TOTALLY WRONG most of the HID kit on the ebay market is DC not AC unless they have stated as DC are at least half cheaper than AC and they still do the job until something happen a bit later. Your call. I have people come back with a DC ballast which is flickering all the time when you point your headlight to a wall or at the back of another car. However, you can actually tell if the ballast is DC sometimes by looking at the starter box. Some really cheap DC ballast do not have the back cover at the back of the starter box. I just threw a pair of DC ballast which I have taken off from a car. I will see if I can find one.