The mail order is up on their page, but still no dimensiones. So I e-mailed them yesterday evening and this morning they have already answered. Seems like their costumer service has improved a lot.
Size 0 Teens: diameter 40mm
Size I : diameter 43mm
Size II: diameter 47mm
As they say there's no need to trim it so I guess it's with the stem. I asked about the capacity,let's see if they give me that as well. I'm rather heavy so I will only concider buying it if it can hold more than my large yuuki. They stated it has the biggest capacity on the market.