1、DIY Mobile Power Supply: Large capacity, 6pcs 21700 batteries (excluding batteries). Dual USB mobile power supply can charge two devices at the same time. Three input ports, any USB cable can charge the mobile power supply. 2、Intelligent 21700 Battery Charger: DIY power bank box is compatible with 21700 lithium battery (not included). Each battery slot is charged and tested separately. The battery will automatically stop charging when fully charged. (Note: please pay attention to the positive and negative poles). 3、LCD Display: 21700 battery power bank case can accurately display the power and keep track of the battery status. Plug and play. USB port is used for power output, and data cable is inserted to realize portability and charging at any time. 4、Wide Range of Applications: 21700 battery power bank box is compatible with all types of mobile phones for charging. It has a wide range of uses and is your necessary gift. 5、Small and Lightweight: 21700 battery charger case is small and light, easy to carry, easy to install and uninstall, providing you great using experience.