What are the caps?
IF the cap is not the tank and the cap is not the bdc, then what are you calling a cap? And what are you calling a bdc; if you clearly distinguish between the tank and the bdc then surely you see that the tank is not a bdc tank.
You think somebody in China won't make a coil to fit the Aspire ET "BDC" tank?
If you put a single coil atomiser in the Aspire ET or you redo your own coil but you don't wrap two separate coils just wrap 1 coil, you think that does something to the tank itself?
The Aspire pyrex tank is not a throwaway tank that is designed to get tossed in a few months; If Aspire starts making a triple coil for a new tank but it also works in the ET, do they then have to rewrite and call the ET "BDC" tank something else?
The Protank 3 was designed to use either a new dual coil, or the older single coil that fits on the other protanks; so what should the protank 3 be called a combo tank?
Have you used an Aspire BDC? I think you're misunderstanding. You can't use an Aspire BDC tank with any other coil nor can you use it's BDC for any other tank. This is not like the PT3 where you can use PT2 coils.