As more people use their smartphones and tablets alongside laptop and desktop PCs, the need for storage that works for both PCs and mobile devices only grows. With the Kingston DataTraveler microDuo ($29.95), plugging into your Android device is now just as simple as using a drive on your PC, and both options fit onto one tiny USB key that slips into your pocket.

Design and Features
The microDuo($49.95 at Amazon), like the Leef Bridge (16GB)( at Amazon) and other PC and mobile storage solutions of late, offers both USB and microUSB connectivity. With the microUSB connection, you'll be able to plug the drive into most of your Android smartphones and tablets, as well as some of the new 8-inch Windows tablets, which may not offer full-size USB ports.

A plastic cover keeps dirt and grime out of the microUSB connector, but unlike the Leef Bridge, which has a cover that slides back and forth, the microDuo has a hinged cover that folds up 90 degrees to expose the microUSB plug. The cover features a locking hinge, requiring you to slide the cover out before flipping it up, keeping the cover closed and the plug protected whenever it's not in use.

This drive is also particularly small, just large enough to have a USB plug on one end and a microUSB plug on the other. Thanks to a small lanyard loop, you can attach it to a keychain, which I would strongly recommend. The drive is so small—nearly as small as the tiny Verbatim Store 'n' Go Car Audio USB Drive—that it will be easily lost. The benefit of the tiny size, however, is that it is much less cumbersome than larger drives—like the Leef Bridge—when plugged into your phone or tablet.

Compatibility and Software
The DataTraveler microDuo comes preformatted to FAT32, for plug-and-play compatibility with a wide array of productss. The full-size USB connection will work with all current laptop and desktop PCs (Windows, Mac, Linux), while the microUSB connection will work with Android-equipped (4.0 and up) smartphones and tablets, provided they have USB OTG (On-The-Go) capability. Not all devices offer this capability, and some have it disabled by default. Kingston has a list of compatible ones on the DT microDuo product page.

It also doesn't come with any files preloaded on the drive. You also don't have any baked-in encryption options either, because steps that are simple on a PC—such as entering in long passwords or installing encryption utilities—don't always translate well on a mobile device.

For browsing through any files on the drive, Kingston does recommend using ES File Explorer on Android phones or tablets. It's a simple file manager, but it works well. We also accessed the drive easily using other popular file managers, so your choice of apps is probably fine. Be aware, however, that many file formats commonly used on PC (such as doc, txt and rtf) do not have native support in Android.

Pricing and Performance
From a price perspective, this is one of the most affordable mobile-friendly storage solutions we've seen. Our 32GB review unit has a list price of $29.95, or 93 cents per gigabyte (GB). The 8GB model ($9.95) sells for $1.24 per GB, while the 16GB model ($15.95) is 99 cents per GB. As usual, larger capacities tend to have a lower per-gigabyte expense, but all three are very reasonably priced. The Leef Bridge, which also offers USB and microUSB connectivity, comes in 16, 32, and 64GB capacities, and sells for roughly $1 per gigabyte, while the PhotoFast i-FlashDrive, which also offers connections for iOS devices, sells for $5-10 per GB, depending upon the capacity.

Kingston covers the microDuo with a five-year warranty, with free technical support. This is considerably longer than competing products, which generally come with a one-year warranty only.

Using the full-size USB 2.0 connection, I tested the DataTraveler microDuo in our timed file transfer test, copying large (1GB+) files back and forth to measure average read and write speeds. With standard USB connectivity to a PC, the DT microDuo averaged 41.5MBps (read) and 6.6MBps (write). By comparison, the Leef Bridge averaged speeds of 17.8MBps (read) and 8.6MBps (write), making it slower when accessing files on the drive, but a little faster when writing new data to the drive. But while these speeds are available over full-size USB, don't expect similar performance when connected to a phone or tablet, as performance varies widely from one device to the next, and is significantly slower overall. These slower speeds will be most evident when transferring larger files, such as video or music files, but individual documents and photos should transfer relatively quickly.

Conclusion
The Kingston DataTraveler microDuo (32GB) offers a simple solution to users who need to transfer files back and forth between a laptop or desktop PC and mobile device, with a tiny design that's easy to take anywhere. It comes with some of the same caveats as the Leef Bridge—it has incomplete Android support and no support for iOS products—but the smaller design and ease of use are enough to make it our Editors' Choice for mobile-friendly USB drives.

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