Gigabit Ethernet Fiber Media Converter - unit was repleaced with 

https://thorbroadcast.com/product/10-100-1000mbps-fast-eherernet-gigabit-ethernet-fiber-media-converter-with-sfp-8230.html

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The F-4G is used for transporting four Gigabit Ethernet ports over a fiber from one location to another. The units work in pairs with a transceiver on each end of the link. Any network cable connected to the RJ-45 port one one unit is transported to the corresponding RJ-45 port on the second unit. Our units work transparently, meaning they are non-IP addressable and any network traffic traveling through the the fiber link remains unmodified. Any two devices that are connected over the fiber link appear to be directly connected by a standard network cable. This is useful for connecting switches or other network devices in different buildings or for extending an IP network to a far away location. We also offer custom equipment to incorporate more signals onto a single fiber. In addition to Ethernet you can also carry video and audio channels, telephone lines, E1 or T1 links, or even satellite signals all over a single fiber. Our units have a maximum transmission distance of 120 km when used with singlemode fiber. We feature easy to read diagnostic LED's for continuous monitoring of link status and network speed. Contact a sales representative for more information.
 

• 1000 Mbps Full Duplex Gigabit Ethernet Over Fiber Transceiver
• 4 x 1000BASE-TX LAN Fiber Port (multimode or singlemode optics)
• 1 x 1000BASE-FX WAN Fiber Port (singlemode optics 1310, 1550, CWDM, DWDM)
• 110km Transmission Range
• 1 or 2 Fiber Strand Transmission
• Full wire-rate 2000 Mbps Duplex Transmission for greater network performance
• Plug-n-Play Gigabit Ethernet Mode Converter or Singlemode Repeater
• IEEE 802.3z compliant
• Guaranteed Switch performance and hardware compatibility with other switches, hubs and adapters