Thank you for viewing! (^_^) Heat-generating, heat-retaining, and made of a non-stiff stretch material. These are tabi inner socks made with Toray "Soft Thermo" yarn. They have heat-generating and heat-retaining functions, which will be useful in the coming cold season. M size: 22.5-24.5cm They have been stored unused and unopened. There appear to be no stains, but since they are unopened, there may be oversight. How about it? (*^^*)