You bought a highly insulated jacket. The fill power is right. The collar fits. Then you wear it in real cold—and you notice something: certain lines across your back and chest feel noticeably colder than the rest. Not everywhere—just along specific horizontal and vertical seams. You're not ...

Most people buy “the warmest jacket they can afford” and then sweat, freeze, or both. Lab work on multi-layer clothing shows that total comfort comes from how layers work together, not from one monster parka. This guide explains the base–mid–shell system using real insulation and comfort data so ...