These powerful Varta Rechargeable 9v size batteries are 8.4V 200mAh NiMH batteries. The 200mAh rating is a measurement of the battery's capacity. The higher the mAh rating the longer the battery will last in an appliance. Varta rechargeable 9V size batteries are pre-charged in the Varta factory and are ready to use as soon as you take them out of the pack.