I recently received a bunch of these re-tension frames but I have never seen anything like them. The owner of them had passed away and his wife didn't seem to know anything about them. I would like to put new mesh on all of them, but I have no idea how to use them or what kind of wrench is needed. It looks like it is as easy as an allen wrench but I can't see down inside the holes too well. I cannot seem to find any manufacturer info on them either.