Check this video, you will get the idea.
https://www.youtube.com/watch?v=KFr5GmViLug
These films/eyes can be bought cheap and are a lifesaver when you have to check such items like tone rings embedded into oil seals.
I have had to redo a Honda wheel bearing which was interference fit into the spindle because the supplied part had a broken tone ring in the oil seal (bad brand new part from a very good japanese brand).
So guess who checks them every single time now.
