Smartodoors 3200mAh External Backup Battery Power Case for Samsung Galaxy Note 2 II N7100 (Black-With Stand) The other end contact to either an USB power adapter or an USB socket of a computer. To charge the phone, simply slide the phone into the portable battery and slide on-off switch to on. Also can be used as a good case to protect your phone from scratches and other minor damages. A perfect emergency backup when the internal battery of your device is drained on the go. Ideal for long distance travel or business trip.