Male Q/C to male Q/C adapter plug, useful item for transitioning between your compressor and diving tank, w/out needing to remove your hose when you need to fill your rifle. 

Manufactured from stainless steel and may need a bit of buffing to encourage it to fit in better. Otherwise, works perfectly.

The centre has a 12mm hexagon, 3.51mm in height, which you can toggle w/ a size 12 metric spanner, should that ever be necessary.

Please note that this is a micro-quick coupler fitting, meaning the lip measures in ø8mm (which the female Q/C catches onto), so please don't mistake it for the larger variant.

The length per male Q/C on these bits is 11.80mm

Whereas the bore is ø3.6mm.