XO is visions most advanced fly line. It has vision's new STD taper making it one of the easiest casting all round fly lines. XO has a super slick and strong HiFlo coating. It also features varying hardness coatings in different parts of the line; the head being softer allowing you to push arrow shaped tight loops and the running line being harder for carrying extra-long overhangs and ultimate shootability. Due to XO's long rear taper and the fact that the line casts well no matter how much head is out Vision felt that the line doesn't have to be two-toned.