So far I have been using two different PV's that are from name brand companies. NLA and Green SMoke. There Cartomizers seem only to fit their models. Now My first mod is in the mail and on the way. The Provape1. But that brings up a question. How does this work? It is coming with a 510 fitting. NOW FOR THE QUESTION....510,901, 808, these relate to the threading? if so, when I go to many of the Vendor sites, like V4L, they don't say what size there carts fit? DO I have this wrong?