James , tefer2 has something there, they could also be the vent/plugs that was used to plug the holes drilled in the side of an existing house when blowing insulation into the walls. They really used to build houses with zero insulation. I haven't seen any around for some time, they use a different type now. You may find some at a mom & pop hardware place that has a box or so left over. You could also check with a company that does retro-fit blown-in insulation for some leftovers.