External auxiliary battery of 4,000 mAh manufactured in aluminium. With USB output and Micro USB input. LED charge status indicators and Micro USB charging cable included. Available in a wide range of colours and presented in an individual kraft design box, with instruction manual in English and Spanish.Micro USB input: 5V DC 1AUSB output: 5V DC 1AThe capacities shown in all our external auxiliary batteries are real, all of them incorporating non-recycled, grade A batteries, with a service life of at least 500 charging cycles, and complying with CE regulations. In addition, they are manufactured according RoHS standards, and in compliance with the following safety requirements: Power bank overcharge protection system. Complete discharge protection system, which increases the durability of the power bank. Blocking system to prevent short circuits. Constant charging transfer system, in accordance with the capacity of the target device.