Ok, so I found out that the Van Helium in a Small is 32-36, a Medium is 36-40, a Large is a 40-44, an XL is 44-48 and a XXL 48-52. Hope this helps eveyone. Now keep in mind that I am not 100% for sure on these. I found the Large and XL sizes on a post in Wake World. So I just used common sense to figure out the other sizes. I'd say I'm 93.5% sure...