Elgato introduced the world's first bus-powered Thunderbolt external hard drive, the Elgato Thunderbolt SSD, at CES 2012. The drive is based on an internal solid-state drive and is available in 128GB and 256GB capacities.
The new Elgato Thunderbolt SSD is about the same size as other portable drives that are based on the 2.5-inch internal drives often found in notebooks.
The Elgato itself is based on an SATA 6Gbps solid-state drive, the fastest internal drive type on the market. This is because the Thunderbolt standard offers even faster than that in terms of bandwidth--up to 10Gbps.
Currently, Apple offers only one size for the Thunderbolt cable, which works better for desktop drives than for a portable drive like the Elgato Thunderbolt SSD. Elgato said that there will soon be a new Thunderbolt cable that's shorter and possibly even thinner which would better suit the portable solution.