This is another GameCube accessory that I've owned for quite some time now. As you could tell from the image or the product's name, it is a cable used to connect between the GameCube and gameboy advance. Each side is designed to perfectly fit into the corresponding consoles without falling and being lose. Which means you can connect between the games safely without any risk of damaging your game. Because of the way the adapter is designed it will only work on gameboy advance and gameboy advance consoles. It won't work with a gameboy micro on normal circumstances. This later inspired wireless connections between future games from Nintendo.
At the time when I bought this, the cable was easy to find, but I honestly can't remember how much the original recommended retail price was. I can only assume it was around a tenner, because I can't imagine that it was cheap. There are cheaper unofficial versions of the cable that can be bought for as little as 99p and some are selling for £30 so I guess it's safe to say it was between the £15 area. I remember it was bought at gamestation around nine or eight years ago. In my experience, it has always been better to use official products because they tend to work better and be more value for money in the long run.
Your need for the cable greatly depends on what games you have on the GameCube and the Gameboy advance. A lot of the pokemon games that were released during this era will use this cable for transporting pokemon from the gamecube to GBA or the other way around. The Harry Potter and some of the sports games can work as well, but you'll find the list of what games use the cable on Wikipedia and I've pasted the link in the review's summary.
I've used the cable for my pokemon games. From my experience, I've found them very useful. The game will usually tell you when you can connect your gamecube and GBA game together. It always tells me when to connect and the connection rarely fails. It's useful for downloading exclusive items or special games onto your GBA.
This is another GameCube accessory that has never failed me. But if you have the gameboy player adapted on the GameCube, you should be aware that the the cable won't work with multi-player modes and you need to use a GBA link cable or the nintendo universal link cable to do multi-player games between those games on the gameboy player.
It hasn't let me down and I think it's been a good device. I think it was worth the money, however much I paid into it. I'd probably would recommend it, but you need to check if you have the games that would support the games first. Do a bit of research on it because this cable is useless if you don't have games that will support it.
It looks like I'll be having more people round often. A lot of my friends have used my cable because this is so rare and hard to come across now.