The F1DU4001320 is 4 10/100M Base-TX to 100Base-FX media converter.  The converter complies with IEEE 802.3 standards. It is designed to convert data signals between 10/100 Base-TX and 100 Base Fx Fast Ethernet. The media converter is connected between fiber cable and twisted cable segments of the network to convert optical signals to electrical signals and vice versa. BiDi WDM - Wave Division Multiplexing Technology allows you to use a 1 fiber cable instead of 2, because transmit and receive channels are separated by different wavelengths.