What is the furor behind these 3 inch spinning gadgets?

Seems like These little suckers are popping up everywhere. Stores can’t keep them in stock. Parents are going crazy trying to find them. The mania for the fidget spinners is truly unlike many other toy crazes to date.  

Believe it or not, versions of Fidget spinners have actually been out for years, mostly used by kids with Autism or Attention disorders to help them concentrate.  But recently, out of nowhere, they mysteriously exploded in to popularity this spring.