As computers and other digital devices become more pervasive, the need to transfer files between machines becomes greater. Sony this week at the Las Vegas Comdex IT show unveiled its MicroVault, a stylish and cool new keychain device designed to make this task easier.

The MicroVault is a chunk of Flash memory that can hang on a keychain. Available in 16, 32, 64 and 128MB capacities the device is small, portable and doesn't come with all the hassles of memory cards which require dedicated drives or adapters and often special drivers too. However, this convenience comes at a not-so-cool premium price — there's a surprise.

Like competing products, it gets around these hassles by employing a USB interface, which means it can connect to almost any personal computer. Machines running Microsoft's Windows 2000, Me or XP, or Apple's Mac OS 9.0 and above, don't require a driver to be installed — at least in theory.

Other machines will require a driver but it's a standard one supplied with the MicroVault and might already be on your system. It also includes Sony's Privacy Zone software, which allows users to create a password-protected area for storage of personal files.

With a loop so that it can be attached to a keychain, the small device is certainly cool — an attribute not unusual in a Sony product. But people will have to decide on what premium they attach to this coolness: the cheapest MicroVault, the 16MB version, will carry price tag of £35 or more; the 128MB version could cost more than £200.

This is more expensive than a Sony Memory Stick module of the same capacity. The price difference gets larger as the capacity increases, with the 128MB MicroVault costing double the price of the equivalent Memory Stick.

And while the MicroVault will connect to personal computers, it won't be able to connect to, say, a digital still camera via USB for image storage. That function will have to wait for the new USB On-The-Go system, which is still being finalised. Just like memory cards, the MicroVault does not require a battery because flash memory only needs power when data is being read or written, and that can be gained from the USB cable.

The MicroVault will be available first in the US, in January 2002, and Sony plans to follow with launches in other markets, although timing has not been decided.