Never heard of them before myself. If we assume for the moment that they have accurately portrayed themselves on their website:

The American Iron Front is a network of Americans participating in direct action to counter the fascist and anti-democracy agenda perpetuated by groups and individuals in the United States. This agenda is being perpetuated by mainstream parties and fringe groups alike through misinformation, pseudo-patriotism, and weaponization of the law to disenfranchise voters, women, minorities, and those that oppose their bigoted agenda. They are actively recruiting in the cities and towns of America and radicalizing recruits online.

Our goal is to stand as a direct counterpoint to the nationalism of the alt-right and its corruption of American values by building solidarity, unity, and common defense of the Constitution.

https://www.ironfrontusa.org/about-us

Edit: Based on imagery alone (see wikipedia page), I would guess the organization is inspired by this: https://en.wikipedia.org/wiki/Iron_Front

The Iron Front (German: Eiserne Front) was a German paramilitary organization in the Weimar Republic which consisted of social democrats, trade unionists, and democratic socialists. Its main goal was to defend democratic socialism and liberal democracy against totalitarian ideologies on the far-right and far-left. The Iron Front chiefly opposed the Sturmabteilung (SA) wing of the Nazi Party and the Antifaschistische Aktion wing of the Communist Party of Germany.[1] Formally independent, it was intimately associated with the Social Democratic Party of Germany (SPD). The Three Arrows, originally designed for the Iron Front, became a well-known social democratic symbol representing resistance against monarchism, Nazism, and Marxism-Leninism during the parliamentary elections in November 1932. The Three Arrows were later adopted by the SPD itself.[2]