Action Replay (Game Hacker)

This allows you to put cheats and hacks into your games. For example, you could spawn whatever Pokemon you wanted, shiny even. Or you could have invincible mode in New Super Mario Bros. it contains cheats for a lot more. You insert the DS cartridge into this accessory, and then put the action replay into the DS, then you can select the cheat from there and then start the game.

It's in good condition other than the sticker part being a little worn.