What is thermal underwear made of? How high is its warmth retention component? Is there a national standard?
Heida Marie HIDAMARI health thermal underwear, imported from Japan, ultra-thin, and the thermal effect is comparable to that of down jacket. It is the favorite of climbers on Mount Everest. It has a three-layer structure, the inner layer is always dry, and the sweat is automatically discharged to the outer layer, which is sweat-proof and moisture-proof, and has a heat preservation effect even if it is wet.