A boost of power wherever you go! Convenient, portable power backup for small usb electronic devices. Replaces all other usb chargers for total portability. Can charge devices through usb port up to 70% of full power. Makes device with dead batteries operational within 5-10 minutes. Powered by two replaceable, rechargeable nimh or alkaline aa batteries. To charge nimh batteries: connect charging cable from computer's usb port into power booster's mini-or micro-usb ports. To charge small usb powered electronics: connect device to power booster using usb cable provided or one of your own led indicator light shows the device is charging and battery status. Includes usb charging cable and 2 rechargeable nimh aa batteries. Sturdy clip allows you to take the power booster everywhere.