Wig-wag

[automobile] A wig-wag is a device for flashing an automobile`s headlamps at a preset rate. Traditionally{says who?|date=May 2014}, the wig-wag will flash the right and left headlamps—often the high beams—alternately, but some designs{vague|date=May 2014} will flash both headlights on and off together.{CN|date=May 2014} More complex wig
Found on http://en.wikipedia.org/wiki/Wig-wag_(automobile)
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