This is a brand new Panasonic CR1616 coin cell battery with tabs. If your GameBoy game is failing to save properly the most likely cause is a faulty save game battery.

All GameBoy games use either a CR1616 or CR2025 coin cell battery. In order to determine which type you need open up your game. The existing battery should have a CR number printed on it. If you cannot read the number measure the diameter of the battery. CR1616 batteries are 16mm wide and CR2025 batteries are 20mm wide. Those games that use CR2025 batteries can instead use CR2032 batteries, which will last five years longer. We also sell CR2032 batteries.

You will need a security tool to open your game cartridge which are sold separately. All GameBoy Original and GameBoy Color games use a 3.8 security screw, while GameBoy Advance games use a triwing screw driver. 

Installation does require soldering skills and equipment, although step by step color instructions are available for download.