The 400G QSFP-DD LR4 transceiver supports connections of up to 10 kilometers over single-mode fiber and uses LC connectors. The wavelengths are 1296 to 1309nm.
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.