According to statistics, the vast majority of men use either the 45mm (1¾") or 50mm (2") cock and ball rings
Please Note:
The purpose of a cock ring is to increase the erection, but not to cut off the blood supply. If you experience pain or discolouration, take the ring off immediately. If you cannot remove the ring due to the swelling try some lubricant or an ice pack. If this fails do not hesitate to go to the hospital emergency room. Don’t worry, they have seen it all before.
You can read on this subject in more detail in the Info drop-down menu. This is especially recommended to all newcomers, but old hands may learn something new as well