Summary: I have three of these for my 2011 iMac. They plug into the thunderbolt port and have the ability to add SSD without the difficult process of removing the screen. I also have one of their Goflex drives and it is speedy, as well.
Summary: I am on my second replacement drive and give up; it's not worth trying for a third warranty replacement. I don't know if it just doesn't like Macs or if it just doesn't work, but it often refuses to mount, and DiskUtility warns me that it's not repairable and to back up all my files. I thought it was my Firewire cable, but same with the USB cable. Considered it possible that it had an issue with my iMac and tried it with a Power Mac. I give up.
Summary: Works as it should, providing USB 3.0 capability to Seagate FreeAgent GoFlex drives. If you already have one of these drives with USB 2.0 base, than this is what you want. If you don't, then you are probably better off getting a good hard drive enclosure and 3.5" SATA drive to fill it. I wish this base also allowed eSata connectivity, but Seagate seems to be ignoring that connection type all together.
Summary: The drive stopped working 1 month after warranty and I lost all my information. Only thing you can do is send it in to Seagate for a couple hundred dollars to extract the data. I was very disappointed in Seagate's customer service. I couldn't get in contact with anyone for days and when I did, they gave me wrong information for getting replacement parts.
Summary: Worse external I have ever owned. 1st one died within the year I bought it, replaced it under warranty and the 2nd one did not even last another year. Waste of money and I'll never purchase a Seagate for as long as I live. I wanted to try and recover some data by another reader I had in hopes that the 2nd one just failed but the hard drive is enclosed 100% with cheap plastic so you cannot get to the disk itself.
Summary: Lovely little add on if you have an older GoFlex external drive and want to boost it up to modern USB 3.0 standards. Snap off the old base, put this one on, plug into a 3.0 connector or hub and watch your speeds zoom. The best kind of engineering: You just use it and it works. Major praise to SeaGate for making a cheap way to keep a drive up to date without tossing the whole thing out or having to redo anything whatsoever..