The MiLi iData Pro is a nifty USB flash drive that does not merely add more storage to your iOS devices. It also allows you to transfer files among iOS and Android devices as well as Windows and Mac PCs.

Around the size of Apple Watch's face, this rectangular device looks like its competitor Hyper iStick from far. But iData does not have iStick's slider mechanism.

Instead, the iData has a cover to protect the Lightning connector at one end, while a USB 3.0 port at the other end is unprotected.

The device has a nice metallic premium feel. It comes in gold, rose gold and silver, so you can pick one that suits your iPhone. But it is not as slim and lightweight as the SanDisk iXpand Flash Drive I reviewed last month.

The package comes with a USB-to-micro-USB On-The-Go (OTG) adapter and a USB 3.0 cable.

I tested the iData Pro with an Apple iPhone 6s Plus, Samsung Galaxy S7 edge, a late-2012 Apple MacBook Air and a 2015 HP EliteBook 820.

To use the iData Pro on iOS and Android devices, you need to download the iData Pro app. The app supports devices running iOS 8 and above, or Android 4.3 and above with OTG function.

When you first plug the iData into an iOS device, you will be prompted to download the app. The app give you access to pictures, music, videos and documents stored in the flash drive.

The app lets you copy files from the iOS device to the flash drive, and vice versa. You can backup contacts using the app, and you can even compress files to take up less storage space.

If your iPhone is running out of space with too many pictures, the app has a camera function that lets you save your photos or videos directly to the flash drive.

However, the camera function is really basic with no additional features such as filters or aspect ratios.

Plugging the iData into an Android device is not as straightforward as I would have liked.

You need to plug the USB 3.0 cable to the iData and the USB-to-micro-USB OTG adapter to the USB cable before you can plug it into an Android device. But, with that done, the app works just like its iOS version.

For PCs and Macs, the iData works just like any USB flash drive. No need to use an app here.

Transfer speeds are quite fast across platforms.

Transferring a 3.25GB folder consisting of documents, pictures and videos from the iData to the HP laptop took 65sec, while moving the same folder to my MacBook Air took only 46sec.

But moving the same folder from iData to an iPhone 6s Plus took 2min 40sec. It took 2min 50sec with the S7 edge.

The best thing about iData is, unlike the iXpand, you can transfer a single file of more than 4GB to the iData, or stream any movie that is larger than 4GB.

• Verdict: The MiLi iData Pro USB flash drive is a tad more expensive than conventional flash drives. But if you have multiple devices in different platforms, this is the USB drive to get.