Tenergy TN145 8-Bay AA/AAA NiMH/NiCd Charger + 8 AA & 8 AAA Premium Batteries Built-in IC timer control for over-charge protection. Short circuit protection and reverse polarity protection Automatic charging current selection for size AA and AAA LED to indicate proper charging. Tenergy Premium AA and AAA size rechargeable Nickel Metal Hydride (Ni-MH) battery, top of the line. Advanced Ni-MH technology means twice as long use life per charge than the ordinary rechargeables. Can be recharged up to 1000 times, providing big saving by replacing hundreds of throw away AA/AAA batteries.