Rayovac 7-Hour Power Recharge USB Backup Charger with Micro USB Cable and Batteries Included (PS79-4B) Powered By 4 Aa Batteries (alkaline, Rechargeable Or Lithium) Each Set Of Alkaline Batteries Provides Up To 7 Hours Talk Time Charges Via Micro Usb Port 4 Led Battery Gauge Indicators Show Discharge Status For Alkaline Aa Batteries & Charge Status For Nimh Aa Batteries Pushbutton Switch Turns Charger On-if Inactive For 30 Seconds, Charger Will Automatically Turn Off To Save Battery Power