In the early 80s I built bikes in department stores for a company called y.l.c.e. we were given park tools, one of which was a 9/16 15mm pedal wrench. We had to build quickly to make a living and I found the pedal wrench invaluable. It worked on huffy one piece cranks and the many chinese bikes with low end square taper cranks. The secret weapon in its body was knocking out the plug in the handle so that you could use it as a cheater bar. In a pinch it was also a small hammer.
I wish i still had that wrench!