I can reduce the thickness of my iPhone 4 to that of the iPhone 5 by simply removing the back panel :/
There's barely any structure added by the back panel in the first place. I'm sure the iPhone 5 has Something Neat about its new construction, but the difference in thickness doesn't really seem all that impressive.
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Yeah the thickness isn't impressive they just removed the back glass I wish they would of maybe kept the same thickness and added a thick battery for more time