Never have to buy a battery again for your Wii fit! This Rechargeable Battery Pack holds charge for a good two weeks if used every day for an hour.Charging is easy and does not take more than an hour. The Rechargeable Battery Pack fits well in the WII Fit Balance board and lasts much longer than ordinary batteries. Working style DC 5V directly electricity input charge. The biggest electricity should no less than 200mA. Wii Fit Battery Pack output DC 4.8 ~ 5.6V, can enough support the machine during working. It's can work after installing the battery pack. With large capacity rechargeable battery, the USB Battery Pack can charge more than five hundred times. Moreover, it can be charging and using at the same time.The Rechargeable Battery Pack lasts much longer than ordinary batteries.