I received the SD that I mentioned before with the 901 fitting. This is my first time using the 901 attys. So far I am not impressed. The only thing that I do not know is if it is the 901,SD, or the 16340 batteries but my 510 nicostick hits much harder and produces alot more vapor than this. I have a 510 adapter on the way so I can see if the SD and batt perform better with the 510. Maybe I am spoiled with the 510 and this is just how the 901 works at 3.7v.
It will be the 901 - the rest is just a battery! The 16340 will be delivering more like 4.2v by the way. You should find the SD with the 510 adapter performs like a freshly charged standard 510 but for much longer...