All About that Base When the mountain calls for an extra layer, this shirt answers. The women's Burton Midweight X Base Layer Crewneck will keep your personal climate under control, so you can worry about important stuff like which run is next and what to eat for lunch. Built-in Climate ControlThe Living Lining reacts to your body temperature, accelerating moisture wicking when you're hot and retaining warmth when you're cold for balanced comfort all day long. Stink Less Sustainable odor control keeps it fresh without limiting breathability. Comfy Fit and Feel Chafe-free seams and four-way stretch feel good no matter how hard you're working or lounging.