I looked all over that site for ML info and couldn't find it lol. OK I see the size difference you are talking about with the cartos, I never knew that was why...so are you saying a dual coil carto is always longer/taller than a single coil one? Cause I have both a dual coil and a single coil from Volcano and they are both the same size. I even had to mark the wrapping as to which was which because I could not tell (the only way I knew was because my tank came with a single coil) and I had ordered the dual coil one with my order.