Based on the characteristics of various jacket materials previously discussed, high-quality down (high-fill-power goose or duck down) and natural shearling (integrated leather and fur) stand out as the two most effective materials for warmth.
High-Fill-Power Down
This material relies on three-dimensional down clusters to trap large amounts of still air; for the same weight, it offers two to three times the thermal efficiency of cotton. High-fill-power down (800 FP or higher) can maintain core body temperature even in extreme cold-such as -30°C-while remaining lightweight and comfortable to wear, making it an excellent choice for frigid environments.
Natural Shearling (Integrated Leather and Fur)
Featuring dense fur and an integral, compact leather backing, this material offers wind resistance far superior to that of standard down jackets. Its measured thermal resistance ranges from 3.5 to 4.2 clo-significantly higher than the 2.0 to 2.8 clo typical of standard down jackets-ensuring more consistent warmth during prolonged exposure to cold winds. It is ideally suited for use in extremely cold regions, such as Northeast China.
