The file is a virtual memory card used by the PCSX2 emulator to store and update cheat databases for the Codebreaker software. While Codebreaker was originally a physical disc for the PS2, modern emulation allows for updated "Day 1" cheat lists to be sideloaded via these memory card files. Download and Implementation
If you cannot find a trusted download, you can update the list yourself: The file is a virtual memory card used