With this adapter, you can convert a “donor” cartridge (an original Snes cartridge) to another game by simply dropping this pcb on the back side of the donor and soldering it to the existing MASK ROM pins. You do NOT need to remove the MASK ROM.

• This Super Nintendo Adaptor PCB supports most 2mb games.

• This donor adaptor is primarily used for games that are 2mb and smaller    

Don't know which board you need? Reading the manual will help you decide. 

I'm looking for the 4mb adaptor: 4mb Adaptor board

Manual: RetroCircuits Adaptor PCB Manual