Seagate Backup Plus 500GB Portable External Hard Drive for Mac USB 3.0 (STBW500900) 500 GB storage capacity with lightning fast USB 3.0 transfer speed (upgrade to Thunderbolt or FireWire 800 with adapter, purchased separately) Use the Save feature to back up user-generated content from your favorite social media networks Share feature allows multiple files to be uploaded to social networks at once Install the downloadable HFS+ driver for PC and use the drive interchangeably between Mac computers and PC's without reformatting