when ETS rings are registered to a birds ring number it also gets the owners union number registered on it, so if someone gets an ETS ring which dose not bear his union number on it this will come as not registered to him when the ring is being assigned to one of his birds, its then up to the person assigning the rings to ask where he got it, as he can re register it in the persons name, so rings taken off birds can be re registered, so not a sporting thing to do taking rings off birds, but what you must remember there are those that dont like ETS.