This cable is the Serial standard DB9, has male to female connections, and is 6 feet long.
Though these connection ends are not standard, they provide a quick and easy solution to adding extra length to your current Null Modem cable. A standard cable has male to male connection ends, but if you want to extend that length, you have to either buy a new cable that is longer or get another standard cable and find an adapter to connect the two together.
This cable shown here, provides another solution. Because it has male to female connection ends, it has the extra cable length and the needed built-in adapter to connect it to another cable.