The Efest K1 is a portable battery charger that you can take with you anywhere. Using a 5V/1A charge, the K1 adapts to charge a wide range of single batteries including 18650, 20700 or 21700 batteries (sold separately). On the face of the K1 is an LED display that will indicate the battery's charge. This is a very straightforward and user-friendly kit that requires no button pressing or settings, you simply insert your battery and plug it in to begin charging. The K1 utilises a Micro-USB charging cable which is included in the kit. For portable battery charging on the go, it doesn't get easier than the K1.