These spinners have backing plates. That's the seat the cone sits on. The center-bolt goes through the cone and screws into the prop-nut. Did you look at the website I linked? You might get a visual there. It's really very common to have spinners like this. I can't think of one spinner in this size range that doesn't have some kind of backing plate. Good luck with it. Look at the site... or just Google "aluminum RC spinners" or something like that, then look at "images" in Google. It's all there.