See this video for Kindle Paperwhite Teardown:
http://www.youtube.com/watch?v=phO4QkHWsVE
It has metallic isolations of every component (processor and memory), so it does not interfere with other eletronic functioning, thus weighting more and (finally) being allowed to be turned on in airplanes all the time:
http://www.fastcompany.com/3018306/f...lane-electroni
The Paperwhite is very well constructed, in a way I doesn't think Nook and Kobo are.