Credit: Cerevo/The Gadgeteer
Image above largely tells the story:
● 6000 mAh battery with a clamp to hold tablet (almost all fit)
● high output USB port for charging tablet or other device
● low output USB port to connect USB keyboard
● Bluetooth to connect tablet to keyboard
● micro USB port for charging battery
http://the-gadgeteer.com/2014/04/02/this-backup-battery-will-let-you-use-a-usb-keyboard-with-your-tablet/
http://enebrick.cerevo.com/en/ / EneBRICK Cerevo 6000 mAh internal battery two USB ports charging mobile devices stand smartphone smart phone tablet pad adjustable clamp adjusters hold 70 degree angle comfortable viewing Bluetooth transmitter USB keyboard full size cramped undersized key layout /
