The shorter flybar would be used for the KSJ style paddles. the stock Ergo paddles thread all the way through to the other side and then jam nutted in place, thats why it is longer. the KSJ style paddles are glued on at the end, and do not go all the way through, that is why you use a shorter flybar for them. It(the shorter bar) will make the cyclic more responsive.

HTH