KM-30D oxygen mask

Message 647:
Hey All, I picked up something rather interesting yesterday. It is a KM-30D Oxygen mask. It is smaller than the KM-32, has the occipital bladder connection, no microphone and a head harness that isn't coming off (Can't be used without the harness). Anyone have any ideas on this mask? It was the first reference to this mask I have. Cheers, Steve N