One of the defining features of USB 3.0 is the SuperSpeed bus, which provides a fourth transfer mode at a signaling rate of 5.0 Gigabits (Gbps) per second. The raw throughput is 4Gbps, and the standard considers it reasonable to achieve 3.2Gbps. Shown here is a comparison of some of the USB 3.0 and USB 2.0 specifications.