The 18650 lithium ion rechargeable battery is an economical alternative to disposable CR123 cells for newer Streamlight flashlights that are designed to accept both. The two bay 18650 Button Top battery charger can recharge one 18650 battery in as little as 3.5 hours" or two batteries in as little as 6.5 hours. The charger features dual input power sources" accepting either 5V USB power or 12VDC power. Dual input power sources provide a wide variety of battery charging options when a wall outlet is not available" such as a PC" power pack or 12VDC automotive power.