Polyster/Spandex. With microban. Anti-microbial. Anti-odor defense. Breathable, moisture-wicking grid fleece. Can zip collar up to turtleneck. Sleeves with thumb holes. ECWCS - Extended/Extreme Cold Weather Clothing System. Military thermal top. Lightweight. Can be worn alone or as a base layer for extra warmth. GI - Government Issued style. Army style. Military style. GEN III. GEN 3. Thermals are great for skiing, camping, hiking, hunting, sleep wear, cold conditions, and much more. Gen III Level II Underwear Top - Sand Tan.