Seagate FreeAgent GoFlex Desk 4 TB USB 3.0 External Hard Drive STAC4000100 World's most versatile external drive - optional GoFlex Desk desktop FireWire 800/USB 2.0 adapter Use on a PC and Mac computer interchangeably without reformatting Easy-to-use pre-loaded backup software with encryption USB 3.0 plug-and-play Includes GoFlex Desk USB 3.0 adapter with capacity gauge display