The Nitecore UI2 is a lightweight, 2 bay, USB li-ion battery charger, perfect for traveling and charging on-the-go. Offering compatibility with a wider variety of batteries, the compact charger can be used with large sized batteries, including 20700 and 21700 cells. The UI2 automatically determines the optimal charging current when a battery is inserted; if below 2.9V the low current charging mode of 100mA will be activated or if over 2.9V the standard mode with a maximum charging current of 800mA is adopted. Featuring a micro USB port, the UI2 is comptaible with various power sources, including mobile sources such as power banks and solar panels, in addition to USB adapters and other USB ports. The Nitecore UI2 has a simple display which indicates the charging status of each slot using three LEDs. The charger provides anti-short circuiting and reverse polarity protection, intelligent thermal protection and automatic termination upon charging completion, to keep your batteries in the best of health. The charger is ompatible with the following Li-ion/IMR batteries: 10340, 10350, 10440, 10500, 12340, 12500, 12650, 13450, 13500, 13650, 14430, 14500, 14650, 16500, 16340 (RCR123), 16650, 17350, 17500, 17650, 17670, 18350, 18490, 18500, 18650, 20700, 21700, 22500, 22650, 25500, 26500, 26650.