Heater first-layer clothing is designed to maintain optimal body temperature, composed of 47% acrylic, 26% polyester, 20% viscose, 7% elastane. The shirt has an extended back. Due to the unique knitting structure, these thermals are very thin, soft, and fit the body perfectly. They are highly elastic, do not restrict movement, and effectively transfer moisture to outer layers, keeping the body dry. These clothes also feature excellent breathability, dry very quickly, and have special seams that do not irritate the skin.