This is how cock ring work, it is placed around the base of the penis.

During sex, they function by exerting pressure on the area near the base of the penis. So penis ring can be used to create a firmer erection, increase the length of time an erection lasts, or increase the size of the penis.

The use of penis ring, before fitting it, you must ensure that you have an erection, then put the ring on the head of the penis and roll the penis ring down the shaft of the penis to the base. It should stay where your penis meets your crotch.

You need a piece of string and a ruler to measure. Wrap the string around the penis and behind the ball. Mark the string where it meets. When you are soft, you should be able to put your fingers between the skin and the strings. When you feel hard, it should be comfortably tight so that you cannot fit in a finger. Determine your size. P.S.Most men are in the 40mm-50mm range and if you’re between sizes, please choose the smaller size.

Cock rings are rings that are worn around the base of the penis and sometimes the testicles which restricts the blood flow out of the penis, helping the wearer have a firmer, longer-lasting erection.