We have this old, I think it was a sign of some kind, anyway it has this steel rod that runs from one leg to the other and that's were you hang your #. We make them out of clothspins and a square piece of balsa that is glued to the clothspin with your channel written on it and when you get to the field and on the off chance a stranger is there you check the numbers to see if anyone is on yours, if not hang up your tag and go fly. We all have our channels marked down and no-one gets a new radio on your channel, if someone new joins and they are on your channel you try and buy them out, if they won't go for it you just have to share. Very,very simple and it works for us as we have had one shootdown in the last ten years.