The 400G QSFP-DD DR4 optical transceiver uses an MPO-12 connector for transmission over SMF (single-mode fiber) and typically supports a reach of up to 500 meters at a central wavelength of 1310nm. The QSFP-DD (Quad Small Form-Factor Pluggable Double Density) is one of the dominant form factors, alongside OSFP. It is an evolution of the QSFP interface. FS provides an expanding portfolio of 400G OSFP/QSFP112/QSFP-DD solutions featuring high-performance, high-bandwidth, and backward compatibility. Digital diagnostics functions are available via a TWI interface as CMIS specified.