Clickfree HD735 C1 750GB Automatic Backup USB 2.0 External Hard Drive, 7200RPM, 16MB, PC/Mac, 735-1003-100 750GB Clickfree HD735 C1 Series Backup External Hard Drive Automatic Backup Feature - No Software Needed! The HD735 offers incremental backup; upon first connection it will automatically find all of the user data files and copy them to the hard drive. While the software\'s default settings will probably be sufficient for most users, it is user-modifiable, providing full control over the backup settings. PC or Mac Compatible