I use authentic VTC4s 90% of the time vaping a .2ohm coil but I only know of 2 sites with definite official VTC4s. If you want to message me I'll tell you where I get them regularly due to my assurance of authenticity and both are single cells sold for 6.99 or 8 dollars even. I have a bunch of them from both sites. Don't be fooled by the awesome prices, they pass every test and the obvious signs of fakes are absent as well. I use them most of the time vaping under .4ohms. I don't know if it's appropriate to advertise sites here so message me if you want real VTC4s. Can't say much about other Sonys but my go to is those particular sonys. If you are a true subohmer these will end your search for batteries that suit your needs. Plus it's a great feeling to own some of the last remaining batteries of this kind. I will post a pic however these I have handy must be disposed of due to fitting them in a brand new Laisimo L1. My hatch has somehow loosened now. Similar to the Snow Wolf 1.5. I didn't know plastic stretched so easily or quickly that this is no longer a problem. Cost me one pair of Sonys though.