You're looking at a USB 3.0-enabled, 2.5", 7200-RPM external hard drive that's only 9-mm thick—quite a feat, considering bare 2.5" internal drives tend to be as thick as 9.5 mm, and higher-capacity ones range up to 12.5 mm. This is no slim terabyte, though; Seagate only packs 320GB of storage capacity into it, and that's the only option it offers. That might make the $99 price tag a tad hard to swallow for the more budget-conscious among us.
Speaking of pricey, pretty-looking things, Seagate says it's going to offer a Mac version of the GoFlex Slim at Apple retail stores next month. The drive will feature the same capacity and price, but it will be formatted using Apple's HFS+ file system out of the box.