SMAKN&reg; 5v Mobile Power Supply USB Battery Charger 18650 Box-Black Brand new and high quality Over-current protection; Over-charge protection; Under voltage protection; Light load protection; Overload protection; Short circuit protection The battery reverse connect protection (any reverse battery 1 section, two, three, won\'t cause any damage to the mobile power box and battery) Three color of power indicator for Charging: Red:0-30%; yellow: 30-60%; green: 60-100% Plug and play, no need of switch over and over again