十分高速で、特に書き込みが速い。

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CrystalDiskMark 3.0.3 x64 (C) 2007-2013 hiyohiyo
Crystal Dew World : http://crystalmark.info/
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* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]
Sequential Read : 89.054 MB/s
Sequential Write : 79.776 MB/s
Random Read 512KB : 79.034 MB/s
Random Write 512KB : 70.179 MB/s
Test : 100 MB [J: 0.0% (0.0/59.6 GB)] (x3)
Date : 2014/06/16 17:24:43
OS : Windows 8.1 Pro [6.3 Build 9600] (x64)

USB2.0でR/W 20MB/s~21MB/s

XperiaZ2でR : 42.2MB/s W : 38.9MB/s (A1 SD Benchアプリ)

高価なので星４とします。