OnCore Portable Backup Battery ETC-500 for $8.45 shipped after coupon code MLCKF08VNL1. Here is a screenshot for your reference. This is a travel charger with USB connector, built-in 1300mAh Polymer Battery with PCBA. The internal battery automatically charges once the external device is fully charged. It works with iPhone and Android phones, and comes with 6 connectors for various devices.