MiPow SP2600 is a kind of universal external battery, which is certified by Apple company. It is compatible with Apple iOS, Android, RIM and Symbian. You can use it on most smart phones, such as Blackberry, HTC, Samsung, Motorola, Sony Ericsson, LG, Nokia, etc. With delicate design, it is easy to carry on the way. One special feature for the power tube 2600 is the light indicator. Not by pressing the on/off button, but just a slight shaking with the power tube, you know how much power is left inside the power tube: red, less than 15%, orange 15-40%, green 40-70%, blue 70-100%.