400G QSFP-DD SR8 is an eight-channel, pluggable, parallel, fiber-optic QSFP Double Density for 2x200-Gigabit Ethernet applications.
400G QSFP-DD
The 400G QSFP-DD Transceiver follows the same port densities system as the QSFP and QSFP28, but the QSFP-DD will support eight lanes instead of four lanes for the QSFP and QSFP28, which double the density.