This Watson Rapid Charger comes with four 1.2V, 2500mAh AA NiMH batteries that are rechargeable up to 500 times. You can use it to charge four of the included batteries or optional AA NiCd, AAA NiMH, or AAA NiCd batteries. The charger's integrated micro-controller ensures that each battery is charged to its full capacity, and automatic charge cut-off prevents overcharging. Should the controller and automatic cut-off function both fail, the safety guard timer will kick in to ensure that the charger still shuts off after 6 hours. The charger also has circuit and polarity protection. Two LED indicators display charging status, and there are also two individually-monitored charging channels. The charger has switching 100-240 VAC power, enabling use all over the world. Its compact outlet prongs can fold in, making the unit more compact for storage.