I don't really know much about mech mods, I mainly use regulated devices, & I get great battery life off them.
Didn't mean to offend, just to educate properly.
The Nemisis is one of the many mods, that does have a positive pin. Therefore, it is safe to use 99.99% of the tanks out there.
With a hybrid mech mod, the positive pin of 510 connection on the atomizer makes direct connection to the battery. Therefore, it needs to stick out further than the atomizer's 510 connection's threads, which is making the negative pole connection. If the positive pin of the atomizer doesn't stick out far enough, a short could be created, which could lead to the battery blowing up.