The base ring helps position the assembly and forms a body-contact interface. Its inner dimensions affect clearance and contact; its shape and connection also affect how the cage sits and moves. That is why the nominal ring size matters—but it does not explain every fit problem.
| Part of the comparison | Why it matters |
|---|---|
| Inner ring dimensions | Describe the opening; oval shapes need more than one axis. |
| Ring profile and attachment | Influence the geometry of contact and the connected cage. |
| Complete assembly | Body shape, weight, closure and any support can also affect movement or pressure. |
Do not treat one symptom as a size diagnosis
Shifting does not automatically mean “choose a smaller ring,” and pinching does not establish a single cause. Inspect the whole supported configuration, including alignment and hardware. Do not tighten an assembly to suppress symptoms.
For the actual selection process, use the ring-size guide and the measuring guide. For a moving assembly, see shifting and rotation. Those guides keep measurement separate from troubleshooting rather than treating diameter as the only variable.
Stop using the device if there is pain, numbness, swelling, discoloration, broken skin, or difficulty urinating. Remove it if you can do so safely; seek urgent medical help if it is stuck or symptoms are severe. Do not force removal or wait for painful pressure to become tolerable.