LaCie’s FastKey is a mutt. It’s not sure whether it wants to be a svelte, mid-capacity SSD or a girthy, high-capacity USB stick.

At least there’s no doubt about the FastKey’s appointments, which are dazzling: blazing USB 3.0 speed, a durable but surprisingly lightweight ruggedized aluminum case, AES 256-bit encryption and up to 120 GB of storage. All squeezed into something that weighs about an ounce and can be clenched in your fist.

Of course, the major gotcha is the heart-palpitating price — $150 for 30 GB, $250 for 60 GB, and $475 for 120 GB.

While it is specifically designed for computers...