A brief discussion about the benefits of using rechargeable & higher voltage batteries with your Surefire, Streamlight, Olight, and other tactical flashlights.
Ready Up Gear 16340s: https://readyupgear.com/product/16340-usb-rechargeable-batteries-2pk/
Ready Up Gear 18650s: https://readyupgear.com/product/18650-usb-rechargeable-batteries-2pk/