Complies with 802. 3u 10/100Base-TX, 100Base-FX standards Auto-negotiation of Half-Duplex/Full-Duplex transfer mode Adopts WDM technology, transmitting and receiving data on one single fiber Extends fiber distance up to 20km What This Product Does TL-FC111B-20 is a 100M media converter, providing a 100M RJ-45 port and a 100M SC fiber port, which can convert between electrical and optical signals. And long-distance data transmission through optical fiber can be applied to commercial scenarios such as park security monitoring and wireless networking. How This Product Works TL-FC111B-20 adopts WDM (wavelength division multiplexing) technology, helping send and receive data at a distance of up to 20 km with only a single mode fiber, which saves half of the cable deployment cost for customers. TL-FC111B-20 transmits data at 1310nm wavelength and receives data at 1550nm wavelength on optical fiber. Therefore, the terminal device used in conjunction with the TL-FC111B-20 should send data at a wavelength of 1550nm and receive data at a wavelength of 1310nm. TP-Link another media converter TL-FC111A-20 is one of the products that can cooperate with TL-FC111B-20.