Buffalo LS-WVL/E unit is a disk network storage (NAS) unit, allowing you to choose your own hard drives for a customizable and scalable storage solution. It is twice as fast as the standard network storage unit and features a high-speed 1.6 GHz processor for maximum transfer speeds up to 72 megabits per second. You can connect it to any network Ethernet port or to the back of your wireless router, and access it via any network-connected device in your home. While on the move, Buffalo's free WebAccess service lets you create a personal cloud for easy remote access and file sharing with anyone, anywhere over the Internet. The included NovaBACKUP software for Windows and Time Machine provides a comprehensive backup solution for all PCs and Mac computers connected to your network....It has 2 hard drives with 4 terabytes of storage each.