Today I went down to my local e-cig store to buy some new juice and a couple new cartomizers. I told the guy that I wanted the 2.5ohm 510 dual coils, as I usually use the smoketech cartos of the same type (I put them in my unit and run them at 6volts). I'm pretty positive that these new cartomizers I bought are the boges. After getting home, I refilled my tank, punched and saturated the new carto, and twisted it into my SB. At first, it simply didn't work. I put in some fresh batteries and still nothing. Finally I decided to try a lower voltage and put in a 3.7 volt battery. Now it seems to work ok. But this is weird because I have always used the smoketech 2.5s at 6 volts and never had a problem. The only thing I can think of is that the guy in the store gave me cartos with the wrong resistance rating. Unlike the smoketechs, these cartos don't say the resistance rating on them, as they are completely blank. Anyone else have any ideas?