Fenix ARB-L18-2300mAh Rechargeable 18650 Battery Button Top Design Protection circuit built in the anode with a steel hat by riveting process. Steel shell eliminates the risk of short circuit caused by collision and impact. Pressure Relief Vent: Expels waste gas generated by internal short circuit. Expelling waste gas prevents a cell from inflating or exploding. Three Sets of Over-Heat Protection: Over charge protection, Over discharge protection, Short circuit protection, and overheating protection 500 Charge Cycles: A properly maintained ARBL18 battery is designed to retain up to 75% of its original capacity at 500 full charge and discharge cycles.