Fast Photonics 400G QSFP-DD DR4 Optical transceiver module are designed for 400 Gigabit links over 500m single mode fiber in the Data Center.It is operating on 1310nm wavelength, compliant with the QSFP-DD MSA and IEEE 802.3bs protocol. Digital diagnostics functions are available via the I2C interface, as specified by the QSFP-DD MSA