The main use case for the MCA4J80 is to link two 800Gb/s Quantum-2 switches to each other (up to 5-meters). The 3-meter, flat and finned-top cable is for linking Quantum-2 switches to DGX-H100 Cedar systems.
Overview
MCA4J80-Nxxx 800Gb_s Twin-port OSFP to 2x400Gb_s OSFP InfiniBand ACC Product Specifications