If you measure the diameter of each of them, you will find that they all differ from each other a bit. This is so that the ends of the points on the star drive come out at the right distance apart to match the drive link spacing. (I don't use 3/8" LP chain, but I believe there is a slight difference between the 3/8" and the 3/8" low profile. This because the length of the pitch is measured at the rivets. Because the links on 3/8" LP is not quite as tall as on the regular 3/8", it sits differently on the drive sprocket.)