I'm almost certain its for the chain gaurd. Supposed totgo around the stay and bolt onto the rear hole to hold it in place, however it rarely actually fits like that. The exhaust bracket is a pretty big thing with two full circles when screwed together that wrap around the muffler and bike frame to hold it in place, though it's so flexible I really don't think it does much. Those things work well for gas tank mounts if you have a large top tube though.