Do Utheral Sounds hurt?

I don't know if I spelt Utheral right, so sorry if not.

If you do not know that a Utheral Sound is, its basically those thin (usually metal, but it can be glass or even liquid) rods that you usually see getting put in the dick-holes of dudes to stop them from cumming. Its usually a form of BDSM.

Anyways, I'm a woman, and im curious: do these rods hurt? do they provoke any pleasure?
Because in the manga/hwa/huas ive read featuring these, ive seen subs both saying it feels good (which im assuming they feel sexual pleasure and no pain) and those who scream about how much it hurts.

I can understand liking the pain, and i guess stimulating the prostate if you go deep enough??

How much do these things hurt???