if it's a slim battery you don't want to use the low resistance stuff because it could damage the battery. if its an ego or riva type battery youll be fine
I'm sorry permafrying... (love that user name) I have to disagree (respectfully). I know they say that, but ... it's hard to explain.... the 1.5 ohm LR (the REALLY LOW RESISTANCE) attys can sometimes damage a eGo or Riva. They draw more amps than it was intended to use. The MOSFETs give out.
OTOH, the slim cig sized
batteries can't produce enough amps to fry the mosfet, but it does stress the battery a bit. The main reason to not use LR on the slims is that they only last an hour or so on a good day with 3.0 ohm atties.
So...
A) for a slim cig-like battery (standard 510)... you can try 2.5 ohm, or even 2.0 ohm if you want... but you'll charge em even more. lol. "Standard" is 3.0 ohm. Lower ohms will stress the battery, but then again, they don't last long anyway (lifetime, not charge-life).
B) for an eGo, I'd personally stay at 2.0 ohms or higher. Others swear by 1.5 ohms, but they also kill eGos
sometimes. YMMV as they say. May also vary according to manufacturer and model-revision. Best you can say is "I'll risk it", or "2.0 Ω is good enough."