Cisco Compatible 1000BASE-SX SFP transceiver module for MMF, 850-nm wavelength The SFP transceiver modules are hot-pluggable I/O devices that plug into module sockets. The transceiver connects the electrical circuitry of the module with the optical or copper network. You can use any combination of SFP modules that your Cisco device supports. The only restrictions are that each port must match the wavelength specifications on the other end of the cable and that the cable must not exceed the stipulated cable length for reliable communications. You may use Cisco Compatible SFP transceiver modules on your Cisco device. Each SFP transceiver module has an internal serial EEPROM that is encoded with security information. This encoding allows Cisco to identify and validate that the SFP transceiver module meets the requirements for the device.