Since the release of the Fenix PD36R and TK22V2, 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! 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 the direct USB charging. For the 21700 battery with Type-C charging click here.Specifications500 Recharge Cycles5000 mAh CapacityLithium-ion rechargeableMultiple Layers of protection Pressure Relief Valve Protection Separate Microporous Protection PTC Cathodal Protection Protection Circuits in the anode Overcharge Over-discharge Short Circuit Overheat Protection 7.5a Maximum current Steel Shell Riveting 3.6V Charging Current: 1A recommended, 5A Maximum Note: Does not include an on-board USB port for direct charging Size Weight: 2.56 Ounces Height: 2.99" Diameter: 0.85"