Scott snap-on leather edgeroll kit 🙂 Works great indeed with the -55 internals. Comms are standard NATO/US. Mask is a HGU-12/p. It’s the combo I used for a few military flights. The French civil Fouga I sometimes fly in has the oxygen system deleted, so I just use a small cable to go from US NATO plug to French(UK helicopter?) plug. I leave the ox hose disconnected, so no need to convert that fitting. I prefer wearing the mask instead of a boom mike for the added protection in case of a bird strike.
I will however have to change the mil earphones with 300ohm civil ones after a recent comm setup change.