Since the release of the Fenix PD36R, everyone has been patiently waiting for the release of spare batteries. The time has come; now available is the Fenix ARB-L21-5000 rechargeable 21700 battery. The all-new Li-ion battery provides the voltage and power needed for extended runtime and higher lumen capacities. The ARB-L21 comes with all the bells and whistles of high-quality Fenix batteries, including protective circuits inside the anode and up to 500 charging cycles. Also included are the three sets of overheat protection: pressure relief, microporous, and PTC cathodal block. Don't run out of light; pick up a spare 21700 battery today!