400 micron is 0.4mm. The iPad in the picture certainly would have more deviation at the ends than that.. --- Post Merged, Jan 7, 2019 --- There was never an iPad Nano But I had the iPod Nano and the scratching issue wasn't as bad as it was said to be. It was a pretty nice device actually. I was sad to have to send it back for a replacement, I got the later square touchscreen iPod but I would have preferred to get the old one back, it was much more beautiful. The square one now failed with a stuck power button, sadly. It won't even turn on anymore.