An external hard drive 2 TB - USB 3.5 2.0, for a very reasonable price. My operating system is Windows 7. Automatic start, SD, after connecting to a USB socket and the stop button open. Driver installation is fast and the HDD is immediately operational. No special knowledge is required for using this external HDD. I use SyncBack as backup tool (Backup) that allows you to make files or directory synchronization (mirroring, instead of copying (stupidly) all files each backup it simply adds files missing and update those modified. Conclusion: Given a delivery on schedule and satisfaction I draw from this material I can only recommend.