Energizer, AA/AAA Pro Charger, 1500Mah With 4 "AA" Battery Cells, Expanded Charging Information Allowing For Ease Of Use, Includes A Unique Design With The Integration Of Sound To Alert The User Throughout The Charging Experience & When There Is A Bad Battery, Integrating Sound Into The Design Of The Charger Allows For A Series Of Beeps To Indicate That The Charging Has Initiated & When The Battery Is Fully Charged, Helps To Maximize Battery Performance.