This is a BRAND NEW ASA, or Air Source Adaptor fitting.  It is also known as a Universal Fill Adaptor, or a pin depressor.  It screws onto any paintball CO2 tank, and when the knob is tightened, it allows the CO2 to flow out of the 1/8" NPT pipe fitting.  This is the fitting that is on the end of a CO2 filling station.  This fitting can also be used to make your own remote line set-up.  It is a direct replacement part on all of our CO2 fill stations, as well as almost every other manufacturer's fill stations as well.