The 3.5ml DCT/SCT tanks are approximately the same diameter as an eGo. They are polypro, so cinnamon is fine. I have a couple.
It's the lower one:
They look kind of cheap, which they are. I got mine for $6.00 from Vapor Phoenix. They come loaded with a single-coil carto (you can use a dual coil in it if that's your thing), but I don't recommend buying replacement cartos from VP. I put Smoktech XLs in mine.
510 SCT-V2 3.5ml Tank