Birdlocked discussion

The Master attempted to place a ring with a 30mm width and 45mm diameter on me, checking if I can manage it comfortably once the birdlocked arrives. She couldn’t get that one onto me, so we switched to a 50mm diameter version. That one went on easily enough, though it fits rather loosely. Is the ring attached to the birdlocked flexible? Will it stretch at all to make insertion easier? The Master believes a 45mm diameter is the correct size for me. However, she tried putting on a piece of PVC plumbing pipe with that same diameter and struggled because it was quite rigid. If the ring can give just a little bit, we should be fine. Could someone please let us know? Thank you, Servant.