USB offers five different transfer speeds: 1.5 MBit per second (called "low speed"), 12 MBit per second ("Full Speed"), 480 MBit/second ("Hi Speed"), 5Gbit per second (called "super speed"), and 10 Gbit/s (“super speed+“). Hi speed is only available in USB 2.0 and later, and Super speed is only available in USB 3.0. These speeds are raw bit rates (in Million bits per second). The actual data rate is usually lower due to protocol overhead.