The 4-pin to 6-pin IEEE 1394a cable connects a 4-pin IEEE 1394a device to a 6-pin IEEE 1394a port on a computer at a transmission rate of up to 400Mbps. This cable is used from a 1394 host to a self-powered device. The 2 power conductors are not used since the peripherals have their own power supplies.''Use the 4-pin cable for non-powered devices, and the 6-pin cable to provide power to devices.