Dont worry about your smartphonelosing power when youre just walking into a concert, when youre getting off the train or when youre in the middle of a serious conversation. The Energizer Instant Charger is ready to use and more than doubles the run time of mobile phones. This pocket-sized, powerful charger can charge your micro USB mobile phones from dead with the power of 3 AA Energizer Ultimate Lithium batteries (included). The cap protects the micro USB when youre not charging and easily snaps onto the bottom of the charger when you are.