The MR21 is an interesting hybrid drive. On the one hand, put it into the supplied 5.25in mobile rack and it hooks up to your system via high-speed SATA. Remove it and you can still hook-up via USB2.0. The downside is that the mobile rack isn't lockable, taking away some of the benefit of this two-in-one device.
Discover more in this COMPUTEX 2007 Headline.