Specifications: Brand: Seagate Name: Seagate Expansion Storage capacity: 500G， 1TB， 2TB， 4TB (optional) Connection: USB 3.0 Hard drive size: 2.5 inches Max transfer rate: 120MB/s Item size: 11.7 * 8.0 * 1.48cm / 4.60 * 3.14 * 0.58in (L * W * H) Item weight: 170g / 5.99oz Package size: 14.5 * 10.5 * 3.2cm / 5.70 * 4.13 * 1.25in (L * W * H) Package weight: 207g / 7.30oz Package List: 1 * Portable hard drive 1 * USB 3.0 cable 1 * User manual (22 languages) Please note: Product needs to be reformatted if it is to be used with Mac. Reformatting the drive will erase all content unless it is backed up to another drive. About capacity: Since the calculation units of hard disk manufacturers and computer operating syst are different， the capacity display will be different. When producing hard disks， the capacity is calculated according to 1G = 1000M = 1000 * 1000K = 1000 * 1000 * 1000BYTE. However， the computer operating system is binary and calculated according to 1G = 1024M = 1024 * 1024K = 1024 * 1024 * 1024BYTE. For example: The actual capacity is the marked capacity of the hard disk 1000G / 1.024 / 1.024 / 1.024 = 931G (1000 ÷ 1.024 ÷ 1.024 ÷ 1.024)， so the display capacity of a 1TB hard disk is 931G.