I ordered both the sigelei and the vtc4 at the same time, while I was almost positive they would work together, and I know the vtc4 is overkill, I didn't want to have to deal with 1700 different kinds of batteries between my mods and vw apvs. I just wanted to make sure that my order of the vtc4s will work in my sigelei so I can get her vaping when it gets here! They were vtc4 flat tops. Work or no workie?