The Nitecore NL2150 21700 battery is the newest addition to their line of portable power. This 21700 cell is specifically designed to be used with high-performance flashlights and specialty electronics. The high capacity of 5000mAh allows your device to have long efficient run times. Protected with integrated overcharging and discharging circuitry, you can be sure that your battery will be safe through charging cycles and extended use. The lithium-ion chemistry not only provides stable, reliable power, but it also allows for recharging up to 500 cycles! Rechargeable batteries save you money in the long run and help the environment at the same time.