Chargeyour batteries with the Efest Slim K2 Charger. The Efest Slim K2 Charger is a high quality with a cost-efficient and portable design. The Efest Slim K2 Charger is a dual slot charger with Micro USB input and charges at 1A. Each slot is monitored independently to provide the most efficient charge. The LED indicates when your battery is charging and when the battery is fully charged. The Efest Slim K2 Charger features reverse polarity, short circuit, overcharge protection and many more safety features. The Efest Slim K2 Charger can charge different types of 3.6V/3.7V lithium batteries commonly used in electronic cigarettes, flashlights, electric tools, and more.