Fenix ARB-L21-5000 V2 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!
THIS BATTERY IS NOT AN 18650, AND IT IS NOT COMPATIBLE WITH 18650 FLASHLIGHTS OR OLDER-STYLE CHARGERS. COMPATIBLE CHARGERS ARE THE ARE-A2, ARE-A4, ARE-D1, OR ARE-D2. This is not the version of the battery with direct USB charging.