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. Easy and simple to use - plug it in and go. Fast file transfers with superspeed USB 3.0. Compatible with USB 3.0 and USB 2.0. Simply plug in the included power supply and USB cable. Automatically recognized by Windows operating system， so there is no software to install or configure needed. Drag and drop file saving， right out of the box. Built-in power management ensures power-saving operation. 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. FAQ: The solution for booting a hard disk drives beyond 2.2 TB. Most legacy syst built before 2011 have a traditional PC BIOS. This type of BIOS uses a Master Boot Record (MBR). The MBR Partitions can define a disk drive capacity up to 2.2TB. Windows operating syst that boot from an MBR are therefore limited to 2.2TB per MBR. Such as a 3TB disk drive in a legacy BIOS and Window system will need a DiscWizard device driver to access the full capacity of a 3TB disk drive. Two partitions will be necessary because of the MBR limitation. The device driver mounts the capacity above 2.2TB with another MBR which looks to the system as a second virtual “physical” device. GUID Partition Tables (GPT) can define drives larger than 2.2TB. You can use GPT today on any Windows 10/ 8.1/8/7 and Vista system as a non-booting data drive. Windows can only boot a GPT partition on a new type of BIOS called UEFI.