Tested every 10 hard drives (5 colors), tested 8 in a row at a speed of 9 - 12 Mbps (USB 2). Ironically, of the 2 black drives, one tested consistently higher (11-18Mbps) and the other black drive significantly lower (0kb - 17kb - 100kb - 4mb). So, not sure what's going on there, but generally good enough for my purposes. I haven't had them long enough to determine durability and as the speed of the 2 black discs varies significantly I'm unsure on quality control. (I would probably give 5 stars if the 2 black disks matched the rest better.)
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