Fast Photonics 100G QSFP28 ER4 Optical transceiver module are designed for 100 Gigabit Ethernet links over 40km single mode fiber.It is a cost-effective, low power optical transceiver with high port densities and compact size. It is compliant with the QSFP28 MSA. Digital diagnostics functions are available via the I2C interface, as specified by the QSFP28 MSA