NEW Fenix Rechargeable 4000mAh 21700 Li-ion Battery--For Your High-Powered 21700 Battery Flashlights
Why another rechargeable battery? The higher current (mAh rating) allows the 21700 battery longer runtimes in flashlights. As is with all Fenix rechargeable batteries, the 21700 4000mAH 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.