Available now at Laylax is the First Factory Outer Barrel Base & Gas Block Base Set for the SIG Air MCX AEG... "A set of an outer barrel base that can be attached to the SIG AIR MCX and a gas block base that can be used with a genuine gas regulator. Since our "outer barrel piece (sold separately)" can be connected between the outer barrel base and the gas block base , the barrel length can be changed to the desired length."