Bi-Directional SFP, aka BiDi SFP or WDM SFP, is a compact optical transceiver module used in bi-directional communications applications. It interfaces a network device mother board (for a switch, router or similar device) to a fiber optic or unshielded twisted pair networking cable. It is a popular industry format supported by several fiber optic component vendors. Fiber-Mart supplies different types of BiDi SFP transceivers for Fast Ethernet, Gigabit Ethernet, Fibre Channel and SONET/SDH etc. These BiDi SFP modules can support transmission distance up to max 120 km.