naive question about cockrings

Hello fellow PEers,

I have a very simple question. I noticed that some guys wear a cock ring (or multiple of cockrings) starting right beneath the gland.

I noticed that when I hear two cock rings (one at the base, the other right beneath the mushroom cap) my unit seems more stretched and the head stays engorged for a long time. Even in flaccid state, the head is a bit bigger (more blood trapped in it).

My simple question is: What is the purpose to wear cock rings right beneath the gland? For bigger head?

Thanks!