This is a 20,000 mAh power bank for recharging cell phones and tablets. It is charged using a USB cable (included) attached to a USB power source up to 2 amps and, when fully charged, will provide 2 devices each up to 2.4 amps of charging power. It is large enough to completely recharge phones 4 to 6 times, and tablets 2 times before reuiring recharging of this device. It is very solidly built and has an LED power meter, that indicates percentage of fully charged and, while charging it displays charge.
I will be keeping this in my briefcase to use in the event that my phone gets low and I am not around my normal charging station. You will be happy with this product, I certainly am.