ReVIVE Series TwinPort 5000mAh DUAL USB Slim and Portable External Battery Charging Pack for HTC , Samsung , Motorola Smartphones and More!
it's very simple and the  weight is very light  i can carry it on my pocket   it came with  one button, press once to check battery level ( read or blue)   you can press and hold to switch  ON/OFF   i charge it for five hour after that i tried to charge my Samsung note and samsung galaxy s plus   the only bad thing on it the USB mini-bolt which use for car charging wall socket on it not standing well and it may make small  electric short   my adapter from 1st use damage but it's not big problem coz still i 