Power your portables with the Rock Solid 10,000mAh External Battery Pack from Tether Tools. This external battery pack provides you with 10,000mAh of charging capacity for your phone, tablet, or any USB-compatible device. It has dual output ports so you can charge up to two devices at once. One of the ports has a 5V, 2.1A power output for fast charging, while the other has a standard 5V, 1A output. With an internal microchip controlling the voltage, the Rock Solid battery pack ensures that your devices will get the power they need without damaging them. When it runs out of battery, recharge it the same way you charge any phone or tablet, via a desktop, laptop, or wall charger.