We stock lithium ion batteries in the 18650 size profile with a flat-top profile. Batteries differ in chemistry and include ICR (lithium cobalt), INR (lithium phosphate) and IMR (lithium maganese). INR and IMR are are recommended for mechanical mods and high-drain applications, e.g. high wattage devices.
There is a trade-off between battery capacity and battery discharge rate (the amp drain that a battery can safely and continuously sustain). Batteries that have the highest capacity tend to have a lower discharge rating than batteries that have less capacity. Users will find a balance that works best for their mod and vaping habits. If pairing batteries in a multiple-battery device, batteries should be of the same make and manufacture, and then "married together" by marking them, e.g. using a permanent marker, so that they are charged and discharged together.