I was out walking Scout last night after dinner and noticed this at the end of a long driveway in our neighborhood. It didn’t have a second one on the other side of the driveway so it wasn’t to mark where the edges of the driveway were for snow or something like that. Best I can figure is that it is there to give a way for the homeowners to tell people coming to their house that they need to turn where the red reflector is. Otherwise, it is hard to see their house and there’s no mailbox or anything like that. “Turn at the red reflector and go up the long driveway.”