This unit is the Seagate Expansion Desktop 4TB external hard drive, a 3.5-inch desktop drive aimed at customers who need a large amount of bulk storage for backups, media libraries or archiving and don't need any of the extra software or encryption features found on Seagate's higher-end lines. At 4TB it comfortably holds a full system backup image alongside a large photo, video or document archive, and being a 3.5-inch desktop mechanism it needs its own external power adapter rather than drawing power from the USB port alone — the trade-off for the extra capacity and lower cost per terabyte compared with a bus-powered portable drive. It connects over USB 3.0, which remains backward compatible with USB 2.0 ports on older machines, and the black enclosure measures a desk-friendly 41.9x125x179mm. Seagate backs the Expansion Desktop range with a 2-year limited warranty.