The ARB-L21-4000P battery supports large current output making it ideal for powering lights and other items that are operated at higher power loads. The maximum current for the ARB-L21-4000P is 18A, with a continuous output current of 10A. The higher current allows the 21700 battery longer runtimes at higher levels in flashlights. As with all Fenix rechargeable batteries, the 21700 4000 mAH has three sets of overheat protection, including pressure relief, microporous, and PTC cathodal block. The pressure relief vents all gas to be expelled; this prevents secondary hazards.

Shipping Note: Lithium ion batteries are considered "dangerous goods" per US transportation regulations and can often only be transported via ground shipment. Orders containing loose batteries will typically take much longer than predicted to be delivered. Delivery times of 14+ days are not uncommon.