Nomenclature H1, H2 , emanates from usual lamps (Halogen).
Simply, in the case xenon, becomes the completion with HID technology for the creation of shine and no with glow of wire.
And a serious info.The type of H4(Halogen), that is to say the existence small and big scale, in the same lamp (FZ1), have been faced with various ways in xenon.
H4-1: we only have a scale, usually intermediate. They exist also with only the big scale, for the FZ6.
H4-2: we have xenon intermediate and (Halogen) big scale. IGNORE.
H4-3: we have lamp, whoever moved, front behind. Under from lamp, exists a metal with suitable configuration, in order that in combination with the movement lamp, we have intermediate and big scale. THE BETTER CHOICE.
H4-4: we have the two lamp xenon, one above the other. It requires 2 Ballast, it has delay in the alternation of scales. IGNORE.