This lets you attach the 1/4 MFL thread on the Quick Disconnects to a female M8 thread.
The M8 thread is the thread on the regulators in the Growl Tap Kit and the Basic Tap Kit.
M8 is the same thread as a bicycle tire if that helps you at all :-)
The technical term for the 1/4 FFL thread is 7/16-20UNF female