Avent Niplette or other niplettes advice

Hi, I’d like to better understand how these work, namely the exact effect they have on the nipple; I haven’t been able to find an answer elsewhere.

It says in various places that after a few months the nipple is “permanently erect. I’d like to know if the nipple and areola region actually go permanently erect, as in engorged and smaller (as normally happens when a nipple goes from soft to erect), or if the nipple itself (in people with flat and inverted nipples only), simply sticks out as if erect, in the same way that most nipples always do whether erect or not? If a person with the common sticking-out nipples used it, would it have any effect? Thanks a lot!