This is the FA9001 – FAB to Cable Crossover Adapter .
Normally, you hook up or connect one FAB Module to another FAB Module directly by mating their corresponding male/female headers together.
If you do not wish to do that, for one reason or another, you need to use this FAB to Cable Adapter to connect the two FAB modules together.
What this FAB9001 adapter does is convert the Female input port of a FAB Module to a Male connector. After the conversion, now you can use a plain ordinary 10-pin ribbon cable (with female/female connectors on both ends) to hookup the two FAB modules together.