BOOT SLOT 2 - This menu option allows the R4 DS, just like M3 DS, to boot the GBA Slot, or Slot 2, in your Nintendo DS / Nintendo ds console. Through those of individuals that want to get may on a GBA Flash card, and would like to run GBA Homebrew games and applications as well as Nintendo ds. It also adds extra storage for NDS Homebrew, since you can actually make use of a GBA Flash card start ND