We ran across this very same problem with trying to find replacement o-rings for the Siren V1's, both the 22mm and the 25mm versions. We never did, and Digiflavor/GeekVape never provided any replacements even though multiple people messaged and emailed them asking for replacements. What we found thru experimenting was that the Sub tank mini and Plus replacement o-ring packs would get us by. I guess that what I am saying is that there is the chance that Vandyvape might Not offer replacement o-ring kits for the Berserker. That is a possibility.