Nitecore Ui1 It is definitely a smart, portable and lightweight charger for easy outdoor charging. The UI1 charger has a charging current of 800mA with optimal charging modes to protect batteries and maximize battery cycle life. With a large slot, the Nitecore UI1 is compatible with 3.7V rechargeable Li-ion batteries and is specially available for 20700 and 21700 large batteries. It also comes with various charging protections and is CE, RoHS, FCC, KC certified and C-TICK.