This is a bare PCB for the KC-MSX-FLASH flashcart for the MSX. It is a bare PCB in bold black. I got it with ENIG finishing and edge beveling, so the edge connector should hold up better. The PCB was designed by MSXLegend and is based on the work by KernelCrash. You can find more information on their GitHubs ( complains if I link directly). This uses a STM32F407 dev board. These can be found here on and elsewhere for under $20 (including shipping), so it is a cheaper way to get a flash cart compared to something like the Carnivore. However, the supported games are limited somewhat.
Let me know if you have any additional questions or need more photos.