The extra bracket is used to isolate the cells from PCB, it can prevent the danger might be caused when the battery is shocking. Thicker and wider nickel sheet is chosen to solder the cells to reduce the cells voltage change and increase the heat dissipation, and then great weld strength of cells can be achieved. High strength ABS material is adopted for housing, hard&strong. Narrow waist design helps you hold the battery steadily, won’t slide from your hand easily. Built-in USB output(5V, 2.1A) can fit to charge mobile phones, Ipad, etc. After getting the USB connected, long-press the LED check button for 3 seconds to start charging.