Men's Cold Weather Fleece-Lined Crew Neck Thermal ECWCS Undershirt Top with Pin Made from polyester material. Durable material that will last a long time. Comfortable outer with fleece lined inside material, that is super soft and extremely comfortable. Part of the ECWCS Clothing System Gear - Extreme Cold Weather Clothing System product. Stretchy crew neck cuff . Double stitched waist to ensure long lasting quality crew. Designed to copy original GI thermals. Choose from our 4 available colors: Black, Desert Sand, Brown or Coyote Brown which is AR 670-1 Army Compliant color. Wear it as thermals, underwear shirt or undershirt and be sure to stay warm during those brutally cold winter days. These thick thermals are exactly what you need during those cold snowy winter windy days.