EnerPlex Jumpr Mini Power Bank for Smartphones, MP3 Players and Other Mobile Devices (JU-MINI-GY) Ultra slim business card sized power bank Provides 50-90% more battery life for most smartphones Tethered micro-usb output Includes a micro-usb Female to USB-A Female adapter, so you can also charge your friends iPhone if they have their Lightning cable with them Charge multiple jumper Mini's simultaneously via innovative magnetic stack and charge capabilities