The new PortaGig 50 builds on the success of the PortaGig 800 and adds a couple cool new features. Bus-powered with FireWire 800 or USB for optimum compatibility, it also includes an eSATA port for the fastest speed possible, up to 100MB/s. eSATA is not a bus-powered interface, however, you can use the eSATA connection for data transfer while simultaneously using the FireWire 800 connection to power the drive. This allows the fastest connection possible and bus power from FireWire. An external power supply is included with the PortaGig 50 if bus power is not available.