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do all of them require 2 usb ports???? one for power and one for data?

anyone have good reccomendations on which one to get?

Many of them seem to have higher power requirements than the good 'retail' units. I played with a couple but found them less versatile than e.g. Freecom 2.5" drives. All my portable 2.5" drives are now Freecom.
 
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