GuardKey USB Encryption Dongle: Plug and Play Encryption for Hard Drives or Cloud Drives Unlimited Encryption Space: Unlike traditional encrypted USB drives, GuardKey encrypts as many files as you can store on your computer, attached drives, or cloud drives, and isn't limited to USB drive storage space. You can even use GuardKey to protect multiple computers. Hassle-Free Security: GuardKey uses military grade 256-bit AES Encryption. Just like a key, plug the GuardKey in to access your secured files. Unplug GuardKey and the files are re-encrypted and hidden from view. Encrypts Hard Drives, Flash Drives and Cloud Drives : Hard drives, external attached drives, flash memory cards, usb drives, and even Cloud drives are supported. GuardKey supports DropBox, Google Drive, OneDrive, ASUS web storage, and Sugarsync. Convenient and Secure Backup Key: In case you lose your GuardKey, it's easy to make a duplicate GuardKey using the provided software, or you can bind your smartphone to your GuardKey and use the Mobile Unlock feature to access your files. Mobile Access and Photo Lock: GuardKey Viewer Mobile App supports mobile access to secured cloud drives as well as Photo Lock. Take photos securely and transfer them easily to your encrypted cloud drive. Supports Windows (Mac support coming soon).