I have no idea, the companies catalogue just says cowhide leather.... the germans are usually such stickers for detail, and all they give me this time is "cowhide"!
Put your stirrup leathers under your saddleflaps. My saddles are like this and I don't get that annoying nip from the leathers if my leg is moving about. As I'm the only one riding my horse I don't need to change the length, but if you do it's similar to tightening the girth.