These socks have a taping structure that supports the three arches of the foot. L size (26-28cm) I used these a few times when I had plantar fasciitis, but I stopped using them now that it's healed because they feel too tight. 《The following is the manufacturer's description》 These socks support the inner longitudinal arch, the outer longitudinal arch, and the transverse arch of the foot, reducing the collapse of the arches, which can easily cause foot-related problems. By supporting the arches, they not only absorb the impact on the legs when landing, but also the foot arches act as springs, providing propulsion.