First, thanks for your answers.
I ever make a search before post, and that time was my fault because i think i made it some time ago ( and dont know why i was thinking i didnt found anything ).
I have just made a search this morning, and i have spent more than an hour reading about these boxes, so Andy, delete this thread when you want, my question was answered dozen times...
Sorry about that.
Thanks to god, that box cames with the bike and cost me nothing, but never installed, it's just new and came with instructions. As i suspect, it's simply a wire splice in a neat box, I'm going with the wire splice, i want to keep my bike as clean as i can and dont want that "fancy" box installed.
2Tracelab, the box is the correct for the MC21, is not a 4stroke one.
Thanks to all !