This is a brand new 600mAH 4.8V NiMH rechargeable battery pack. If your GameBoy Original battery pack no longer holds a charge this is the ideal solution. This battery also includes a 13 ohm fusible resistor, which is often defective as well and should be replaced at the same time as the battery itself. Installation does require soldering skills and equipment, although step-by-step color instructions are available for download. Opening your battery pack requires a 4.5mm security tool bit, which we also sell separately.