The reported preferred girth is 6 to 6.
Since there is no international standard for roll circumference, everyone should measure their own before using it as some kind of girth standard for monitoring their size accurately.
Does that answer your question? So while your head down there is itching to ejaculate, the brain in the head is suspended.
That said the suggestion above is very good, measure your roll if you intend to use it as a rule.
It is soft and flexible making it easy to hit the right spot.
The unreasonable man persists on having the world adapt to him.