Our warmest midlayer for cold days, the M's Thermal 1/4 Zip Top adds warmth on its own, or layer it under your favorite jacket to dial in reliable comfort. A grid-fleece interior traps heat next to-skin without adding bulk or limiting range of motion, and a smooth exterior makes for seamless layering. Smooth faced grid-fleece layers perfectly with our baselayers to provide maximum warmth High collar with a quarter length zipper allows for venting and easy on and off