For customers who need larger drive capacities that we cannot custom-make, we've decided to offer this Western Digital MyBook. It has a pair of 2TB drives internally, which can be configured for either 4TB of total space or 2TB of redundant storage. In addition to that flexibility, this unit offers USB 2.0, eSATA, and Firewire (both 400 and 800) as connection options. This is a great solution for backup if you use the redundant setting, or for any number of other applications.