Would you like to carry around your presentations, some songs or even a movie in your pocket? A pen drive or flash drive with a capacity of 1 giga byte is all you would need.

With dimensions of four inches by an inch, a pen drive is actually just a flash memory chip packaged in a user-friendly USB interface.

The drives are available in various capacities beginning at 16 mega bytes, going up to 1 GB, almost 700 times more storage space than a floppy disk. Capacities of 32MB, 64MB, 128MB, 256MB and 512MB are also available.

The advantage about a pen drive is that it is a plug-and-play device and does not work on any kind of a battery. You can plug in the drive into any USB port in a computer, which is switched on. The drive works like a compressed mobile hard disk drive, where you can read, write, copy, delete and move data.

While data transfer speed vary according to the model and features, high-end pen drives can transfer data up to a speed of 1 MB per second.

What's more, there are pen drives which have an inbuilt MP3 player and a even a 2 megapixel digital camera. "Most drives available today are shock resistant and come with accessories. The flash memory chips can also be upgraded to an extent," explains a dealer.

Unlike a floppy, which has a short life, or a compact disc, which could wear out in a couple of years of extensive use, a pen drive can keep data intact at least for 10 years.

The downside here is that, in case your memory chip fails, there's little you can do about restoring it, although preliminary repairs are possible.

Most electronic multinational companies such as Sony, Imation, IBM, HP, Iomega, Kingston, Samsung, Transcedent, Easy Disk, have a range of pen drives to choose from, which come with additional features.

While there may be marginal differences of prices with different brands, usually the prices are determined on the basis of the capacity and features. A pen drive with a capacity of 256 MB could cost around Rs 2,500, and will go up as the capacity increases.

A 128 MB drive with an MP3 player, FM, voice recording up to 10 hours would come at a price tag of Rs 4,000, while a similar capacity pen drive with the camera is priced around Rs 7,000.

Says a dealer, "Owing to the high compression, pen drives of higher capacity are still priced steep."

There are high-capacity drives of nearly 2 GB available for around Rs 25,000. For corporate executives, who are on the move 24X7, 1GB or 2GB pen drives can prove to be a real blessing. Imagine having to carry just a thumb-sized gadget instead of a bulky laptop!