Milwaukee Tools - XL (dark grey) Part # 401 The Milwaukee® WORKSKIN™ Mid-Weight Base Layer is constructed to handle the demands of hard work in cold conditions. Fast Wicking Sweat Zones underneath the arms and across the upper back move moisture away from the body quickly in high-sweat areas to avoid dampness, cold, and freezing. Durable, long-lasting fabric used in other areas provides more insulation while resisting pilling and fighting odor to extend product life. When worn next-to-skin and under outer layers, WORKSKIN™ manages moisture and body temperature to help tradesmen work dry, stay warm, and stay comfortable in the cold.