Complex sentence: Lighters with piezo-electric ignition typically do not work (if the striking mechanism is improperly aligned) or have great difficulty at altitude and are unsuitable for mountaineering or other high altitude applications.
Split into simpler sentences: Lighters with piezo-electric ignition typically do not work or have great difficulty at altitude, if the striking mechanism is improperly aligned. They are unsuitable for mountaineering or other high altitude applications.