Without a good base layer, the rest of your outfit isn’t able to function as designed. As the first barrier between your skin and the elements; it’s critical a good baselayer be warm, comfortable, and moisture-wicking. Just like the Pant, the Pyrex Extreme shirt is in a class of its own in a durable, well cut upper body base layer. The same proprietary GRIDtech 4-way stretch fabric works as a second skin, providing additional warmth without weight and maximum breathability.