The Extra Protection Hyper Thin Running socks are made using the patented Blister Guard® system. This system incorporates thin-padded Friction Free® Profilen® fibers on the heel, forefoot and toe impact areas of the sock. Profilen’s chemical name is Polytetrafluoroethylene (PTFE). PTFE has the lowest Coefficient of Friction of any solid material. Open mesh stripe vents and mesh arch allow heat to escape which provide exceptional breathability.