Eton BoostBloc 4000mAh Portable Backup Battery Pack-Charger for Smart Phones (two full charges for most phones) and Other Devices (NBOBL4000W) Backup battery pack with rechargeable 4000nAh lithium ion polymer battery Fully charges most smartphones two times when fully charged USB output to charge smartphone LED battery charge indicator and shake unit to check battery level Micro-USB DC input for use with smart phone chargers (iPhone block, etc.)