BK-3HCCA4BA: 4-pack of ENELOOP PRO AA Ni-MH 1.2 volt 2550mAh rechargeable batteries.  PRE-CHARGED & READY TO USE !  They RETAIN THEIR CHARGE when not in use for up to a year ! These rechargeable NiMH batteries are the BEST AA batteries available for your digital devices !  They can be re-charged best with smart Ni-MH battery chargers, such as the BQ-CC17, the Batteries America V-1000, V-6500, and the MAHA charger series (MH-C800D, etc.)