The Fenix ARB-L18-1100P is a 18650 Li-ion rechargeable with a protection circuit in the anode to help prevent short circuits, over charge/discharge and over heating. The battery also includes pressure relief vents which expel waste gas in the rare case of an internal short circuit preventing an explosion.Features1100mAh capacityProtection circuitry to prevent short circuitsPressure vents to prevent explosions500 charge cycles