The Powerex MHRAA4 Rechargeable AA NiMH Batteries (1.2V, 2700mAh) - 4-Pack is a package of 4 AA nickel-metal hydride (NiMH) batteries. They have a voltage of 1.2V and a capacity of 2700mAh. The batteries can be recharged hundreds of times, and because they have memory-free operation, they will not develop memory effect, which can cause batteries to hold less charge. These batteries will retain a charge at or near their full capacities even after hundreds of charges. A battery carrying case is included.