Nitecore UM20 Battery Charger is a USB powered dual Li-ion battery charger with a high definition LCD display screen that shows a real time charging status. The UM20 is compatible with Li-ion / IMR 18650, 18490, 18350, 17670, 17500, 16340 (RCR123), 14500, 10440 sized batteries. The integrated intelligent power management system intelligently detects input power and distributes charging power. The UM20 offers a unique priority mode that offers either battery or USB charging. The UM20 also enables data transfer via USB. No more tangled messes with the rear USB cable winder and grooves to accommodate 2.5mm/3.0mm USB cables. The UM20 is constructed from fire retardant materials and is also designed for optimal heat dissipation.