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.
QSFP+ Transceivers
The Quad Small Form-factor Pluggable (QSFP) Transceivers are a compact, hot-pluggable transceiver used for data communications applications, It interfaces networking hardware to a fiber optic cable.