I been studying the new 6 and up numbers and i don't think they are real.
anyways the ce is basically a revision number like CE2 was out and became popular because it worked well but was disposable the CE3 came out and was rebuildable, the CE4 came out and it was just a slightly redesigned 3 with some different features.
As near as I can tell the 5 is where the real ones are just now getting too, there are only a few companies that are the real designers of what is called a "stardust" clearo.
to give you an idea of how bad the copycating is - there is a company called kanger, they make excellent clearo style
tanks. but there is a company called kangler who is now releasing clearos all the way up to a CE9 designation depending on where you look.
If your interested in clearo's stick with known companies. vision,
smok, Kanger, a good thing to do is stay with well known vendors as they will usually tell you "this is not a vision product is it a knockoff" a vendor named gotvapes is particularly good for this as they have a pretty tight integration with their supplier base, not suggesting you just
buy there it is also good for common knowledge.