Thanks MaverickB,It's just the generational marker. C1 was the first iteration, C2 the second, and so on. C5 is the newest stuff as far as I know. It might stand for "Collection" but that's just a wild guess.
Thanks MaverickB,
It is just a bit confusing as the new line consist of wide range of jackets with all iterations. For example you can buy a new jacket Corse C3 , C4 or C5.