8 minutes ago, Kerry Beal said:Mine is the middle one
The middle one is the one I'm looking at too. It comes in the 500/mm and 1000/mm I mentioned as well as the 13500/inch shown above. I didn't bother mentioning that one because I did the math and it works out to just slightly over 500/mm so I just assumed it was a non-metric variation on the 500.