"Cable, Adapter: Straight Extension, 18"" length: Adapts military U-174/U to Dual General Aviation plugs. This cord is used to adapt the standard military mono U-174/U plug to connect to General Aviation radios in civilian aircraft. The U-174 mono plug is used on military oxygen masks, and flight helmet drop cords. This cord only adapts the plug, does not convert military avionics to civilian. Unissued."