Aluminum; Slim power bank emergency battery charger with soft PU leather-like accent wrap body; Power/Technology: Rechargeable Lithium Polymer battery; Capacity: 4000 mAh; Input: DC 5V/1000mA; Output: DC 5V/2100mA; Power banks typically retains 80-90% of original capacity resulting in expected lifespan of 400-500 charges and discharges; Charge time differs by device. Charge power bank prior to first use; Includes 4 LED indicator lights: lights are illuminated when device is fully charged (flash or blink while charging). Lights will turn off one by one as power is drained from device use; Includes instruction manual and micro USB to USB-A power bank charging cable; phone charging cables not included; FCC approved.