I got these out of a junk yard off a 521 years back knowing I'd eventually need them and I don't remember if they go between the race and seal or between the race and hub. They are the 521 inner nla 32kb02 nsk brand. I've seen them with the rings installed and without. I'm currently changing one and was not going to use the black ring as the one that came out doesn't have one but was just wondering about them.
So where does it go and why?