I am selling an item purchased from the YAMAP store that has only been opened and never used. Unused, no stains, and has not been cut at all. Size: 25.0-26.0 cm. YAMAP and BMZ have collaborated to develop hiking insoles for those who "want to improve their performance in the mountains" and "want to walk more comfortably," as well as those who have problems such as "feeling discomfort in their feet while hiking" or "getting tired easily while walking." This "Hiking Insole / Carbon" is the highest-end, high-performance model in the lineup. The "Hiking Insole / Carbon" was developed especially for situations where the feet are under heavy load, such as long hikes, long-distance trekking, and hiking with heavy loads, and as the name suggests, it features carbon. By incorporating carbon in the center of the insole, it provides moderate resilience, reducing the burden on the feet. The function of the foot is to balance, absorb shock, and kick off for walking, all at the same time. Especially in hiking, the soles of the feet are subjected to forces two or three times the body weight during walking. Sturdy materials are needed to support that load. Therefore, among various materials, carbon was adopted as the only material that can fulfill the three roles of the foot. By the way, at the 2014 Sochi Olympics, Japanese athletes used BMZ's carbon-integrated insoles in four of the eight medals they won. It is a material recognized by top-level athletes. The manufacturing method of the carbon used by BMZ is very special. The carbon fiber is produced in Japan, and the resin impregnation for shaping is done in Germany, and then sent back to Japan for product manufacturing. Although it can be manufactured entirely domestically, it cannot match the performance of the German process. Because it is carbon made with time, effort, and cost, it is only used in the flagship model. Quoted from the YAMAP store.