I have sent an 8GB one of these back and forth from UK to Australia 14 times now. Just popped into a standard air mail envelope each time. The contents are downloaded and replaced each time. No sign of it wearing out yet.
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I also keep a couple loose in my pocket, for swoppling progs, data, etc, from friends when visiting. Much more convenient that messing about burning disks, but more expensive to give away.
Don't be fooled by the catalogue picture, they are actually smaller than they look. 25mm x 12mm x 2.5mm.