Master has tried to fit a 45mm diameter ring 30mm wide to see weather I am going to be okay wearing the birdlocked when it arrives. She was not able to get it on me so we tried a 50mm diameter and that did go on but it is quite loose. Is the ring on the birdlocked flexible and will it stretch at all to help get it on. Master thinks a 45mm diameter the right size but she is trying to put on a 45mm diameter piece of pvc plumbing pipe and being quite ridged she could not get it on me. If the ring is will stretch a bit we will be fine .can anyone please let us know. Thanks Servant.