Mostly snake oil. A small amount of NAA for cell division and elongation. The 50's advertising is fun to read. Many studies by university researchers showing no real benefits.
I read somewhere on this site that it is only usefull if sprayed onto the foliage and even then the concentration of whatever works in it is too low to do any good.
I can't find the link to the thread but the dude who said it seemed educated and i found him somewhat convincing so i dropped it from my feeding schedule.