F-tone CFP-40G-10KM, CFP-40G-20KM, CFP-40G-40KM 40G CFP transceiver modules are designed for use in 40 Gigabit Ethernet links over single mode fiber. They are compliant with the CFP MSA1 and IEEE 802.3ba 40GBASE-LR4, 40GBASE-ER4. Digital diagnostics functions are available via an MDIO interface, as specified by the CFP MSA.