This "Action Replay Professional" is actually an "Action Replay Xtreme Special Edition for Pokemon Crystal". I do not know if the first city exists (it is certainly Amazon who gave him that name), and I had never used this kind of object before. To approach the subject in more detail, I can spend a long time to understand it. It is in English but easy to translate (Google Translation). But the worst part is the instruction manual that is in French, do not trust it! It must be the translation beast of another kind of Action Replay because it resembles nothing that we can see on the Game Boy Color screen. So you have to walk the websites to achieve find some explanations (including forums) and this site [...] (thank its author). Many codes of various games are already listed in the cartridge. It is also important to know how the small switch. When you turn on the console, make sure it is positioned to the small center button. Therefore, you access the princial menu where you can activate your codes, then when you start the game with "Start Game" and then "Codes On", he asked you to turn pressed the switch in the other direction, the game start and at that time, turn back the other way. And there you have what you have activated. This may seem difficult to read that way, but with the same time console, it's not that complicated. Namely, too, it is written on the cartridge "Special Edition for Pokemon Crystal", but it works for any game concerned by the Action Replay; it is just the color of the cartridge that is identical to that of Pokemon Crystal. And the box is the same as shown in the photo section. Once understood the system, it is a pleasure to do things we could not do before!