Originally Posted by
Stitchbitch
Are the two tubes attached to anything at the top end? The oxygen connector is a modified MC-3A, but instead of the inlet warning device it has a two pin bayonet fitted, so possibly an AR5 training device or an X-mask. The small port on the side of the connector is normally attached to the Emergency Oxygen hose, the two pin would go to some kind of Personal Equipment Connector or filtered air supply.
My Scott mask has an MC-3A connector and it appears to be the same as the OP photo. The small bayonet fitting is for the bail out bottle but it is threaded to the MC-3A. In other applications the MC-3A may use other fittings in this threaded boss.
