Grey, gas out Quick Disconnect with male flare fitting.
You will also need either a Swivel Nut & Barb Kit or our preference Female Adaptor 1/4" FFL x 5/16" (8mm).
MFL fittings are far superior to the standard barbed ones. No need to heat your
beer line up in hot water, to squeeze over the barb & once the line is plugged into
the FFL fitting, the QD can swivel 360 degrees on the end of the line, which puts
far less stress on your keg post seals.