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I bought two of these at different times.  Both of them had the retail packaging with the Android on them and the model number matched the packaging.The first one was 32GB.  I tested this out with dd on my built-in SD card reader on my MBP and on a GFR204SD USB device and couldn't get more than 8 MB/s average write speed.  Would bounce up and down between 6 and 10.  The Class speed is supposed to be the minimum, not the maximum.  R/W off the HDD was above 20, so that wasn't the bottleneck. Neither is UHS compliant, but I should at least be able to get the Class 10 rating out of this.  Read @ 30 MB/s is pretty accurate.The second one (64GB) I tested by just watching Activity monitor to see if it was in the ballpark.  Bounced between 8 and 10 copying from a hard drive or a RAM disk.  Sounds like probably Class 10.  Read speed to RAM disk was about 24 MB/s.