The 'switchback' LED bulbs simply switch from constant white to flashing amber when you use the turn signal or emergency flashers. They basically function the same as the standard dual filament incandescent bulb.
I have always had a dislike for the amber bulb in the clear lens of the LSC housing, so for years I have used the stealth chrome finish bulbs just for aesthetics. The LED bulb has a white appearance when off and do not distract the eye so much as does the amber bulb. But when on, the bright white light is so much better than amber lamps.