Using technology developed by NASA to insulate space suits, these temperature-regulating insoles keep travelers' feet comfortable so they can explore farther and see more sights. The advanced nano-porous aero gel has the highest insulation value of any solid material, and provides a thermal barrier between your feet and the ground. This ensures that your feet stay warm in winter and cool in summer. Lightweight and thin; just slip them in your shoes and go. Men's fits sizes 8–13. Women's fits sizes 7–10. May need to trim slightly to fit.