I’ve got Efest. I’ve got no problem with diameter, just length.
I got them at Nkon, it was either Efest, iJoy or Vapcell.
They didn’t have any others apart from Enercig but I don’t think they’re very good.
Edit
I just looked it up and they are 70.4mm. If certain brands do fit while others don’t, Wotofo should include that in their info on batteries that are suitable for this device.
I’ve bought the Vapcell 21700 batteries, they are also 70mm long and do fit better but still a little tight. I don’t think I can double wrap them, which I like doing with my batteries to be on the safe side.
I might just leave it in the mod and charge it through there, since it’s only a one battery mod.