A single high capacity, high amp LG HG2 18650 battery.

Specifications:

Typical Capacity: 3000mAh

Nominal Voltage: 3.6V

Cut Off Voltage: 2.5V

Continuous Maximum Charge Current: 4A

Continuous Maximum Discharge Current: 20A constant current, 35A pulse current load

Package Contents:

1 x LG 18650HG2 20A 3000mAh Battery

Capacity (mah) measures the milliamp hours of the battery, or the battery life. The higher this number, the longer your battery will generally last, although usually higher capacity battery have a lower Amp Limit.

Amp Limit measures the number of amps that the battery can support your device outputting at a continuous rate. This means that holding the battery down for longer than approximately one second will be safe at or under this limit. For devices running batteries in parallel, the Amp Limit is multiplied by the number of batteries being used (ie. 2 x Samsung 25R = 40A limit). The Amp Limit required is dependant upon the device and tank/coil system you are using, as well as the power (wattage) you are using it at. For most regulated devices, the Amp Limit will not be a concern as there are built-in safety mechanisms.

Amp Limit shown is shown as Manufacturer's Rating (Mooch's Tested Rating). Generally trust the latter more than the former; sometimes Amp Limits are overstated by the manufacturer, including stating Pulse rather than Continuous ratings.

In Short: Most people will be fine with the Samsung 25R batteries. For those who want a higher Amp Limit and don't mind shorter battery life, choose the Sony VTC4 batteries. For those who want a longer battery life and don't mind a lower Amp Limit, choose the LG HG2 batteries or the Sony VTC6 batteries.