Western Digital Elements Portable SE. Hard drive capacity: 320 GB, Hard drive interface: USB 2.0, USB 3.0, Hard drive size: 63.5 mm (2.5 "). Data transfer rate: 480 Mbit/s. Colour of product: Black. Input voltage: 100 - 240 V. Windows operating systems supported: Windows 7 Professional, Windows Vista Home Premium, Windows XP Professional, Mac operating systems supported: Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, Y