The IEEE 1394b serial interface, better known as FireWire® 800, doubles the speed of the older FireWire 400. It uses a newer 9-pin "beta" connector, which is incompatible with either of the older connectors.
This cable features a male 6-pin "alpha" connector on one end and a male 9-pin "beta" connector on the other end, allowing you to connect FireWire 400 devices to FireWire 800 devices.