mAh: Battery capacity, higher is better, but increases the size of the battery.
Voltage: 7.4V batteries are more suitable for lower-power rifles. 11.1V give you a higher rate of fire but can damage the internals of your rifle.
Voltage: 7.4V batteries are more suitable for lower-power rifles. 11.1V give you a higher rate of fire but can damage the internals of your rifle.