What are AF spanners?

AF refers to American Fine (thread) or Across the Flats. The spanners are in Imperial sizes from 1/4 inch to over 2 inches and will match the size of the distance between the opposite sides of an imperial nut or bolt head exactly. Most common sizes in use are 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4 (lug nuts). At one time, armed with a 7/16 and a1/2 inch you could rule the world ! Used on US, UK, Australian and Indian vehicles well into the 1970s and there are still pockets resisting the metric invasion today.