This is an adapter that converts an RP-SMA board to an SMA antenna. The adapter will connect to any 2.4GHz wireless board or interface cables and will allow you to use an antenna/cable with an SMA connection.
You should not need this adapter with any of our antennas or dev boards. These adapters are listed only to help SparkFun users that have rare or odd antenna coupling needs. Be sure to check out the SMA connector tutorial here for more information on SMA connectors.