The black part is the stock chain cover. The silver part behind it is a “hugger” (as it not only covers more chain, it practically hugs it. What it really hugs though, is the rear tire.)
This view shows more clearly the narrow inverted channel that covers the chain, and the big tire hug. It’s not an exact fit. I’m going to procure ideal fasteners and then slightly and gently modify the hugger into the zone of snugger.
DeedleDoodleDaily 