Fake Canon 600EX-RT Flash
Watch out when you are purchasing a Canon 600EX -RT flash to be sure you are not purchasing a knock-off. They may look like a Canon at first glance, but there are ways to tell if they are a fake. Petapixel has a good article describing the tell-tale signs at : http://petapixel.com/2015/06/25/canon-warns-of-fake-600ex-rt-flashes-here-are-the-telltale-signs/