The Iron Cross was a military decoration of the Kingdom of Prussia, and later of Germany, which was established by King Frederick William III of Prussia and first awarded on 10 March 1813 in Breslau (now Wrocław).

Later, it became a fascist symbol in France, Portugal and other nations. Compare it with Swastika 3.
the Iron Cross today means that you are part of the chopper world, whether it is riding them, building them, or in some other capacity.