Wool, steel, Ksyrium--few words carry as much weight in cycling culture. The Mavic Ksyrium Merino Arm Warmers combine two of the three for cool-weather comfort on the bike. As much as we love steel in our framesets, we're glad that Mavic left it out of the warmers. Because it's metal. And anyway, merino is the ideal choice for natural fibers come fall and spring. Its structure is what all the hollow-core synthetics are based on because it traps micro-pockets of insulating air in order to preserve warmth. Merino is also naturally odor-resistant, which is a big plus for those of us who wash our warmers monthly or seasonally rather than daily. Those properties are enhanced with some synthetic threades in order to add a stretch-and-return quality that keeps the warmers from stretching out and slouching down your arms on damp, cool days when you need them the most.