I love fasttech, great price, free shipping. But since it's coming from Hong Kong, it's soooo slow. Also they're a lot more strict with shipping lithium battery. So there's a possibility of it not even shipping. But besides that, SUPER GREAT DEALS!! Also, lots of clones that work just as great as the real thing.really depends on what ohm you are running. if you are going to run sub ohm builds, you must use batteries that can push out enough amps. why mechs can be dangerous is because people run 0.3~ ohms with the wrong batteries. I use samsung 20r batteries, fasttech says they have discharge of 15A but tests show that they have a max discharge of 22A.
$10.51 Samsung INR18650-20R 3.6V 2000mAh Rechargeable Li-Ion Batteries (2-Pack) - max discharging current 15A / unprotected at FastTech - Worldwide Free Shipping