The High-Speed Serial Link (HSSL) FMC provides 4 eSATA ports that are used to implement 4 bi-directional High-Speed Serial Links. Such physical interfaces are used for HSSL commonly used in space applications such as WizardLink and SpaceFibre.
Additionally, HSSL FMC is equipped with 4x expansion connectors for flex-cable to expand the data ports provided, for example by plugging IngeniArs SpaceWire single port module. In such way, the board could provide 4x HSSL ports + 4x SpaceWire ports.
HSSL FMC can be plugged into all FPGA boards equipped with the common FMC connector.